Deontic Modals for Obligation Trong IELTS – Công Thức & Ví Dụ Band 8.0

Giới Thiệu

Deontic Modals For Obligation là một nhóm động từ khiếm khuyết quan trọng trong kỳ thi IELTS, dùng để diễn tả nghĩa vụ, sự bắt buộc, lời khuyên và sự cần thiết. Các động từ này bao gồm must, have to, should, ought to, need to, và be supposed to – tất cả đều giúp bạn thể hiện mức độ nghĩa vụ khác nhau một cách chính xác và tự nhiên. Theo thống kê từ Cambridge IELTS 10-19, cấu trúc này xuất hiện với tần suất cao trong:

• Speaking: Part 2 (mô tả quy tắc, trách nhiệm) và Part 3 (thảo luận về nghĩa vụ xã hội)
• Writing Task 2: Đặc biệt trong các dạng Opinion, Problem-Solution và Discussion essays
• Writing Task 1: Mô tả quy trình có yêu cầu bắt buộc

Ví dụ vận dụng trong IELTS:

Speaking Part 2 (Describe a rule):
“When I was at university, students had to attend at least 80% of their classes to be eligible for exams.”
→ Phân tích: Diễn tả quy định bắt buộc trong quá khứ

Writing Task 2 (Problem-Solution essay):
“Governments must implement stricter regulations to combat climate change effectively.”
→ Phân tích: Thể hiện nghĩa vụ mạnh mẽ, cần thiết

Speaking Part 3 (Discussing responsibilities):
“Young people should learn financial management skills before they start working.”
→ Phân tích: Đưa ra lời khuyên, khuyến nghị

Writing Task 2 (Opinion essay):
“Employees need to adapt to technological changes to remain competitive in the job market.”
→ Phân tích: Diễn tả sự cần thiết logic

Speaking Part 1 (Daily routines):
“I have to wake up early on weekdays because my office is quite far from home.”
→ Phân tích: Mô tả nghĩa vụ cá nhân do hoàn cảnh

Trong bài viết này, bạn sẽ học:

✅ Định nghĩa và sự khác biệt giữa các Deontic Modals
✅ Công thức chi tiết với từng mức độ nghĩa vụ
✅ Cách vận dụng vào 4 kỹ năng IELTS
✅ 25+ câu ví dụ Band 7-9 phân tích chi tiết
✅ Các biến thể nâng cao cho Band 8+
✅ Lỗi thường gặp của người Việt và cách tránh
✅ Bài tập thực hành có đáp án chi tiết

Deontic Modals for Obligation Là Gì?

Định Nghĩa

Deontic Modals for Obligation là nhóm động từ khiếm khuyết (modal verbs) được sử dụng để diễn tả các mức độ nghĩa vụ, trách nhiệm, sự bắt buộc, lời khuyên hoặc sự cần thiết khác nhau. “Deontic” (từ tiếng Hy Lạp “deon” nghĩa là “nghĩa vụ”) chỉ việc đánh giá hành động dựa trên các quy tắc, đạo đức hoặc kỳ vọng xã hội.

Chức năng chính:

• Diễn tả nghĩa vụ mạnh: Must, have to (bắt buộc phải làm)
• Đưa ra lời khuyên: Should, ought to (nên làm)
• Thể hiện sự cần thiết: Need to (cần phải làm)
• Mô tả kỳ vọng: Be supposed to (được cho là phải làm)
• Diễn tả nghĩa vụ yếu hơn: Had better, be required to

Khi nào dùng trong IELTS:

• Speaking: Mô tả quy tắc, trách nhiệm cá nhân, đưa ra ý kiến về nghĩa vụ xã hội
• Writing: Đưa ra giải pháp, khuyến nghị, thể hiện quan điểm về trách nhiệm
• Thảo luận vấn đề xã hội: Môi trường, giáo dục, công nghệ, sức khỏe

Tần Suất Xuất Hiện Trong IELTS

Theo phân tích từ Cambridge IELTS 10-19:

Speaking:

• Part 1: Tần suất trung bình – Câu hỏi về thói quen, quy tắc hàng ngày

  • “Do you have to wear a uniform at work?”
  • “What should tourists know about your country?”

• Part 2: Tần suất cao – Mô tả quy tắc, trách nhiệm, lời khuyên nhận được

  • “Describe a rule that is important in your school or work”
  • “Talk about advice you received from someone”

• Part 3: Tần suất rất cao – Thảo luận về nghĩa vụ xã hội, trách nhiệm

  • “Should parents be responsible for their children’s behavior?”
  • “What must governments do to protect the environment?”

Writing:

• Task 1: Tần suất thấp đến trung bình – Mô tả quy trình có bước bắt buộc

  • Process diagrams: “The mixture must be heated to 100 degrees”

• Task 2: Tần suất rất cao – Tất cả dạng bài

  • Opinion: “People should take responsibility for…”
  • Problem-Solution: “Governments must implement…”
  • Discussion: “Students have to balance…”

Listening/Reading:

• Xuất hiện thường xuyên trong academic contexts, instructions, regulations
• Cần nhận diện để hiểu yêu cầu, quy tắc và mức độ bắt buộc chính xác

Band Score Impact:

• Band 6: Sử dụng must/should cơ bản nhưng lặp lại, thiếu đa dạng
• Band 7: Dùng được nhiều modal verbs khác nhau (must, should, have to, need to) một cách chính xác
• Band 8-9: Vận dụng linh hoạt toàn bộ hệ thống, bao gồm ought to, be supposed to, had better; hiểu rõ sự khác biệt tinh tế

Các loại Deontic Modals cho Obligation thường gặp trong IELTS với mức độ nghĩa vụ tăng dần

Công Thức & Cấu Trúc

Must – Nghĩa Vụ Mạnh Mẽ

📌 CÔNG THỨC CHÍNH:

┌─────────────────────────────────────────────┐
│ Subject + must + base verb + complement     │
│                                             │
│ Ví dụ: Students must submit their essays   │
│        before the deadline.                 │
└─────────────────────────────────────────────┘

Thành phần câu:

• Subject (Chủ ngữ): Người/vật thực hiện hành động
• Must: Modal verb diễn tả nghĩa vụ mạnh, bắt buộc (không chia theo ngôi)
• Base verb: Động từ nguyên thể không “to”
• Complement: Bổ ngữ hoàn thiện ý nghĩa

Ý nghĩa & Cách dùng:

• Diễn tả nghĩa vụ rất mạnh, luật lệ, quy định bắt buộc
• Thể hiện quan điểm cá nhân mạnh mẽ của người nói
• Thường dùng trong văn viết trang trọng, luật pháp, quy tắc

Ví dụ phân tích chi tiết:

Câu 1: “All passengers must wear seat belts during takeoff and landing.”

Phân tích:

• Subject: All passengers (chủ ngữ số nhiều)
• Modal: must (nghĩa vụ bắt buộc – quy định an toàn)
• Main verb: wear (động từ nguyên thể)
• Object: seat belts (tân ngữ)
• Time expression: during takeoff and landing (trạng ngữ thời gian)

Câu 2: “Governments must address climate change urgently.”

Phân tích:

• Subject: Governments (chủ ngữ)
• Modal: must (nghĩa vụ mạnh – quan điểm người viết)
• Main verb: address (giải quyết)
• Object: climate change (vấn đề)
• Adverb: urgently (trạng ngữ cách thức)

Dạng phủ định:

Subject + must not (mustn't) + base verb
= cấm đoán, không được phép

Ví dụ: "Students mustn't use mobile phones during the exam."

Lưu ý quan trọng: Must không có dạng quá khứ. Dùng “had to” cho quá khứ.

Have To / Has To – Nghĩa Vụ Do Hoàn Cảnh Bên Ngoài

📌 CÔNG THỨC CHÍNH:

┌─────────────────────────────────────────────┐
│ Subject + have/has to + base verb           │
│                                             │
│ Ví dụ: I have to work overtime this week.  │
│        She has to attend a meeting.         │
└─────────────────────────────────────────────┘

Đặc điểm:

• Diễn tả nghĩa vụ do hoàn cảnh bên ngoài (không phải ý muốn cá nhân)
• Có thể chia theo thời và ngôi: have to / has to / had to / will have to
• Phổ biến hơn must trong văn nói

Ví dụ phân tích:

Câu 1: “Employees have to complete safety training before starting work.”

Phân tích:

• Subject: Employees (số nhiều → dùng have)
• Semi-modal: have to (nghĩa vụ do quy định công ty)
• Main verb: complete (hoàn thành)
• Object: safety training (khóa đào tạo)
• Time clause: before starting work

Câu 2: “She has to commute two hours every day because she lives far from the office.”

Phân tích:

• Subject: She (ngôi thứ 3 số ít → dùng has)
• Semi-modal: has to (nghĩa vụ do hoàn cảnh)
• Main verb: commute (đi lại)
• Time expression: two hours every day
• Reason clause: because… (giải thích nguyên nhân)

Các thời:

Present: have to / has to
Past: had to
Future: will have to
Present Perfect: have/has had to

Ví dụ:
- Present: "I have to wake up early on weekdays."
- Past: "Yesterday, I had to stay late at work."
- Future: "Next month, we will have to relocate to a new office."

Dạng phủ định:

Subject + don't/doesn't have to + base verb
= không cần phải (không có nghĩa vụ)

Ví dụ: "You don't have to wear formal clothes to the party."
(Khác với mustn't = cấm đoán)

Should / Ought To – Lời Khuyên & Khuyến Nghị

📌 CÔNG THỨC CHÍNH:

┌─────────────────────────────────────────────┐
│ Subject + should/ought to + base verb       │
│                                             │
│ Ví dụ: Students should study regularly.    │
│        People ought to respect the elderly. │
└─────────────────────────────────────────────┘

Đặc điểm:

• Diễn tả lời khuyên, khuyến nghị (không bắt buộc)
• Should phổ biến hơn ought to trong cả nói và viết
• Ought to trang trọng hơn, thường dùng trong văn viết academic
• Thể hiện nghĩa vụ đạo đức hoặc logic

Ví dụ phân tích:

Câu 1: “Young people should develop critical thinking skills to succeed in the modern workplace.”

Phân tích:

• Subject: Young people
• Modal: should (lời khuyên mang tính logic)
• Main verb: develop (phát triển)
• Object: critical thinking skills
• Purpose clause: to succeed… (mục đích)
• Band 8+ features: academic vocabulary, clear reasoning

Câu 2: “Parents ought to spend quality time with their children rather than focusing solely on material needs.”

Phân tích:

• Subject: Parents
• Modal: ought to (khuyến nghị mang tính đạo đức)
• Main verb: spend
• Object: quality time
• Prepositional phrase: with their children
• Contrast: rather than… (so sánh đối lập)

Dạng phủ định:

Subject + should not (shouldn't) / ought not to + base verb
= không nên

Ví dụ: "Students shouldn't rely too heavily on technology for learning."

Should vs Ought to – Sự khác biệt tinh tế:

Tiêu chí	Should	Ought to
Tần suất	Rất phổ biến	Ít phổ biến hơn
Văn nói	Tự nhiên	Trang trọng
Văn viết	Phổ biến	Formal hơn
Ngữ cảnh	Mọi tình huống	Moral/ethical advice
IELTS	Band 6-7	Band 8+ (nếu dùng đúng)

Sự khác biệt giữa Must Have To và Should trong diễn tả nghĩa vụ tiếng Anh IELTS

Need To – Sự Cần Thiết

📌 CÔNG THỨC CHÍNH:

┌─────────────────────────────────────────────┐
│ Subject + need to + base verb               │
│                                             │
│ Ví dụ: Companies need to invest in          │
│        employee training.                   │
└─────────────────────────────────────────────┘

Đặc điểm:

• Diễn tả sự cần thiết logic, thực tế
• Mạnh hơn should nhưng yếu hơn must
• Thường đi kèm lý do hoặc kết quả
• Rất phổ biến trong IELTS Writing Task 2

Ví dụ phân tích:

Câu 1: “To combat rising obesity rates, governments need to promote healthier lifestyles through education campaigns.”

Phân tích:

• Purpose phrase: To combat… (mục đích đặt đầu câu – Band 7+)
• Subject: governments
• Semi-modal: need to (sự cần thiết logic)
• Main verb: promote
• Object: healthier lifestyles
• Method: through education campaigns
• Sentence type: Complex (có mệnh đề phụ)

Câu 2: “Students need to manage their time effectively if they want to achieve academic success.”

Phân tích:

• Subject: Students
• Semi-modal: need to
• Main verb: manage
• Object: their time
• Adverb: effectively (trạng ngữ cách thức)
• Conditional clause: if they want… (điều kiện)

Dạng phủ định:

Subject + don't/doesn't need to + base verb
= không cần phải (tương tự don't have to)

Ví dụ: "You don't need to bring any documents to the first meeting."

Need to vs Need (động từ thường):

Need to (semi-modal): I need to study. (cần phải học)
Need (verb): I need a pen. (cần một cái bút)

Be Supposed To – Kỳ Vọng & Quy Định

📌 CÔNG THỨC CHÍNH:

┌─────────────────────────────────────────────┐
│ Subject + am/is/are supposed to + base verb │
│                                             │
│ Ví dụ: Students are supposed to arrive     │
│        15 minutes before the exam starts.   │
└─────────────────────────────────────────────┘

Đặc điểm:

• Diễn tả kỳ vọng, quy định (nhưng có thể không thực hiện)
• Thường hàm ý reality khác với expectation
• Chia theo thời: am/is/are (hiện tại), was/were (quá khứ)
• Phổ biến trong văn nói

Ví dụ phân tích:

Câu 1: “Employees are supposed to check their emails regularly, but many ignore this policy.”

Phân tích:

• Subject: Employees
• Be: are (số nhiều)
• Supposed to: check (quy định/kỳ vọng)
• Object: their emails
• Adverb: regularly
• Contrast clause: but many ignore… (thực tế khác)
• Implied meaning: Quy định tồn tại nhưng không được tuân thủ nghiêm

Câu 2: “The meeting was supposed to start at 9 AM, but the manager arrived late.”

Phân tích:

• Subject: The meeting
• Be: was (quá khứ)
• Supposed to: start (kế hoạch/kỳ vọng)
• Time: at 9 AM
• Contrast: but… (thực tế khác kế hoạch)

Dạng phủ định:

Subject + am/is/are not supposed to + base verb
= không được phép, không nên (theo quy định)

Ví dụ: "Students are not supposed to leave the classroom during the test."

Had Better – Lời Khuyên Mạnh Với Hệ Quả

📌 CÔNG THỨC CHÍNH:

┌─────────────────────────────────────────────┐
│ Subject + had better ('d better) + base verb│
│                                             │
│ Ví dụ: You'd better start preparing early, │
│        or you'll fail the exam.             │
└─────────────────────────────────────────────┘

Đặc điểm:

• Lời khuyên mạnh mẽ với cảnh báo về hậu quả tiêu cực
• Thường có hàm ý threat hoặc warning
• Dùng trong văn nói, không trang trọng lắm
• Không dùng nhiều trong IELTS Writing (trừ Informal Letter)

Ví dụ:

“Students had better attend all lectures, otherwise they will struggle with the final exam.”
→ Lời khuyên mạnh + hệ quả tiêu cực

Cách Vận Dụng Vào IELTS

Speaking Part 1 – Introduction & Interview

Topic thường gặp: Daily routines, Rules, Responsibilities, Studying

Câu hỏi & Trả lời:

Q1: “Do you have to wake up early every day?”

A (Band 7): “Yes, I have to get up at 6 AM on weekdays because I need to commute to my office, which is quite far from home. However, I don’t have to wake up early on weekends, so I usually sleep in until 9 or 10.”

→ Phân tích: Sử dụng have to (nghĩa vụ do hoàn cảnh) + need to (sự cần thiết) + don’t have to (không có nghĩa vụ). Natural flow, clear reasoning.

Q2: “What rules do you have to follow at work?”

A (Band 8): “Well, there are several regulations we must adhere to. For instance, employees must clock in by 8:30 AM, and we’re supposed to attend weekly meetings every Monday. We also have to submit monthly reports, though honestly, some people don’t really stick to the deadline strictly. I think we should be more disciplined about following these rules.”

→ Phân tích: Variety of modals (must adhere to, supposed to, have to, should) + natural speech fillers + personal opinion. Band 8 features: variety, natural flow, critical thinking.

Q3: “What should tourists know about your country?”

A (Band 7-8): “Visitors should definitely respect local customs, especially when visiting temples or religious sites. They ought to dress modestly and need to remove their shoes before entering. Also, they shouldn’t take photos without permission in certain areas. I’d say tourists must also be careful with traffic because the roads can be quite chaotic in big cities.”

→ Phân tích: Multiple modals showing different obligation levels, practical advice, cultural awareness. Strong variety = higher band score.

Speaking Part 2 – Long Turn

Cue Card Example:

Describe a rule that is important in your school or workplace

You should say:

• What the rule is
• Why this rule exists
• How people follow it
• And explain whether you think this rule is effective

Sample Answer (Band 8-9):

“I’d like to talk about a regulation at my university that all students must attend at least 80% of their classes to be eligible for the final exam. This rule was implemented several years ago because the administration noticed that many students were skipping lectures and then failing their exams.

The rationale behind this policy is quite logical – professors believe that students need to participate in classroom discussions and ought to learn from face-to-face interactions, not just from textbooks. Therefore, attendance has to be monitored strictly through a digital system where we have to scan our student cards when entering the classroom.

In terms of compliance, I’d say most students follow this rule quite seriously because they mustn’t miss more than 20% of classes, otherwise they’ll be disqualified from taking the exam. However, some students are supposed to attend but sometimes they ask their friends to scan their cards for them, which is technically cheating.

Personally, I think this rule is effective to some extent. It does ensure that students show up physically, but it should be accompanied by more engaging teaching methods. Perhaps universities need to focus more on making lectures interesting rather than just enforcing attendance. Students ought to want to attend classes voluntarily, not because they’re forced to.”

→ Phân tích Band 8-9 features:

• Variety: 8 different modals/semi-modals used naturally
• Accuracy: All forms grammatically correct
• Coherence: Logical flow with clear paragraphing
• Critical thinking: Personal evaluation at the end
• Vocabulary: administration, rationale, compliance, disqualified
• Complex structures: Combined with reason clauses, conditionals

Speaking Part 3 – Discussion

Topic: Social Responsibilities

Q1: “Should parents be responsible for their children’s behavior in public?”

A (Band 8): “Absolutely. I strongly believe that parents must take responsibility for how their children behave in public spaces. Young children don’t yet understand social norms, so parents need to teach them proper conduct from an early age. However, I don’t think parents should be blamed entirely if teenagers misbehave, because adolescents ought to start taking personal responsibility for their actions. Society also has a role to play – schools must provide moral education, and communities should create environments where children can learn positive behaviors.”

→ Phân tích: Multiple perspectives, nuanced argument, variety of modals, advanced vocabulary.

Q2: “What must governments do to protect the environment?”

A (Band 9): “There are several crucial steps that governments must implement urgently. First and foremost, they need to enforce stricter regulations on industrial emissions because companies won’t voluntarily reduce pollution if it affects their profits. Additionally, governments should invest heavily in renewable energy infrastructure – this isn’t optional anymore; it’s something they have to prioritize if we want a sustainable future.

Moreover, I think authorities ought to introduce incentive programs to encourage citizens to adopt eco-friendly practices. For example, people shouldn’t have to pay extra for choosing green alternatives; in fact, governments should subsidize environmentally friendly products to make them more accessible.

That said, while governments must lead these initiatives, individuals also need to recognize their personal responsibility. We can’t expect governments to solve everything – citizens must change their consumption habits and lifestyle choices as well.”

→ Phán tích Band 9 features:

• Sophisticated argumentation: Multiple perspectives, cause-effect reasoning
• Modal variety: 11 different modal uses with perfect accuracy
• Complex sentences: Conditional clauses, reason clauses, contrast
• Topic-specific vocabulary: emissions, infrastructure, incentive programs, subsidize
• Natural discourse markers: First and foremost, Additionally, Moreover, That said
• Critical evaluation: Balanced view acknowledging different stakeholders

Cách sử dụng Deontic Modals hiệu quả trong IELTS Speaking các Part

Writing Task 2 – Opinion Essay

Topic: Some people think that parents should teach children how to be good members of society. Others believe that school is the place to learn this. Discuss both views and give your opinion.

Sample Paragraph (Band 8-9):

“On one hand, those who advocate for parental responsibility argue that families must play the primary role in moral education. Children spend their formative years at home, where they first learn fundamental values such as respect, honesty, and empathy. Parents need to model appropriate behavior because young children tend to imitate what they observe. Furthermore, moral development should begin in early childhood, long before formal schooling commences. Therefore, parents have a duty to instill ethical principles through daily interactions and guidance. However, critics contend that not all parents possess the skills or knowledge required for this task, suggesting that schools ought to provide standardized moral education to ensure all children receive consistent guidance.

Conversely, proponents of school-based moral education maintain that educational institutions must assume greater responsibility for teaching social values. Schools can offer structured curricula designed by experts who understand child development. Teachers are trained to address diverse learning needs and can present moral concepts systematically. Moreover, schools provide environments where children need to interact with peers from various backgrounds, allowing them to practice social skills in real situations. Students must learn to cooperate, resolve conflicts, and respect differences – lessons that naturally emerge in classroom settings. Additionally, schools should complement parental teachings by reinforcing positive behaviors and correcting misconceptions.

In my opinion, both institutions need to work collaboratively rather than in isolation. While parents must establish the foundation of moral education at home, schools should reinforce and expand upon these principles. Society cannot expect either parents or teachers alone to bear the entire responsibility. Instead, we ought to recognize that moral development requires consistent messaging from multiple sources. Governments should support both families and schools through parenting programs and comprehensive moral education curricula, ensuring children have the best possible chance to become responsible citizens.”

→ Phân tích Band 8-9 features:

• Thesis-driven structure: Clear argument development
• Modal variety: 15+ different uses across paragraphs
• Academic collocations: assume responsibility, instill principles, standardized education
• Complex sentences: Multiple clauses, subordination
• Cohesion: However, Conversely, Moreover, Additionally, In my opinion
• Sophisticated reasoning: Cause-effect, contrast, synthesis of ideas
• Balanced argumentation: Both views explored thoroughly before personal position

Writing Task 2 – Problem-Solution Essay

Topic: Many people today are concerned about climate change. What are the causes of this problem, and what measures should be taken to address it?

Sample Body Paragraph (Band 8):

“To tackle climate change effectively, multiple stakeholders must take decisive action. First and foremost, governments need to implement stringent environmental regulations that limit carbon emissions from industrial activities. Major corporations should be required to transition to renewable energy sources within specified timeframes, and authorities must enforce substantial penalties for non-compliance. Additionally, governments ought to invest in public transportation infrastructure to reduce dependence on private vehicles, which contribute significantly to air pollution.

Individuals also have a responsibility to modify their consumption patterns and lifestyle choices. People should reduce their use of single-use plastics and ought to embrace sustainable alternatives. Consumers need to become more conscious of their carbon footprint and must pressure companies to adopt environmentally friendly practices through their purchasing decisions. Furthermore, educational institutions should incorporate environmental education into their curricula so that future generations understand the importance of conservation from an early age.”

→ Phân tích: Clear solution structure, variety of obligation modals showing different responsibilities, logical progression from government to individual level.

Writing Task 1 – Process Diagram

Topic: The diagram below shows the process of recycling plastic bottles.

Sample Paragraph:

“The recycling process begins when consumers must dispose of plastic bottles in designated recycling bins. Subsequently, collection trucks transport these materials to recycling facilities, where workers need to sort the bottles by type and color. Contaminated items have to be removed to ensure quality. The sorted bottles then must be shredded into small flakes, which are supposed to undergo a thorough cleaning process to eliminate labels and residues. Next, the cleaned flakes need to be melted at specific temperatures and should be filtered to remove any remaining impurities. Finally, the purified plastic has to be molded into pellets, which manufacturers can use to produce new products.”

→ Phân tích: Appropriate use of modals for describing necessary steps in a process, passive voice combined with modals, sequential organization.

Nâng Cao – Cách Dùng Để Đạt Band 8+

Kết Hợp Với Các Cấu Trúc Khác

Deontic Modals + Passive Voice

Formula: Subject + modal + be + past participle

Ví dụ 1: “Strict measures must be taken immediately to prevent the spread of infectious diseases.”
→ Band 8+ features: Passive construction emphasizes the action rather than the actor, formal academic tone, urgency conveyed through “immediately”

Ví dụ 2: “Environmental regulations should be enforced more rigorously to ensure corporate accountability.”
→ Phân tích: Passive voice + modal + adverb of degree (more rigorously) creates sophisticated structure

Ví dụ 3: “Students’ progress needs to be monitored regularly by both teachers and parents.”
→ Phân tích: Combination of modal + passive + agent (by teachers and parents)

Deontic Modals + Perfect Infinitive

Formula: Subject + modal + have + past participle (talking about past obligations/advice)

Ví dụ 1: “The government should have implemented these policies years ago to prevent the current crisis.”
→ Band 9 features: Expresses regret about unmet past obligation, critical thinking, cause-effect reasoning

Ví dụ 2: “Students ought to have started preparing for the exam earlier rather than cramming at the last minute.”
→ Phân tích: Past advice not followed + contrast with reality (cramming)

Ví dụ 3: “Companies must have conducted thorough research before launching products in international markets.”
→ Phân tích: Logical deduction about past necessity

Deontic Modals + Conditional Clauses

Formula: If + condition, subject + modal + base verb

Ví dụ 1: “If governments want to reduce traffic congestion, they must invest in public transportation infrastructure and should discourage private car use through taxation.”
→ Band 8+ features: Complex conditional, multiple modals, specific solutions

Ví dụ 2: “Unless immediate action is taken, temperatures will continue to rise, and nations will have to face catastrophic consequences.”
→ Phân tích: Unless clause + future modal obligation + dramatic vocabulary

Ví dụ 3: “Should citizens wish to improve their quality of life, they ought to participate actively in community development and must hold their elected officials accountable.”
→ Band 9 features: Inverted conditional (Should citizens wish = If citizens wish), formal tone, civic responsibility

Deontic Modals + Relative Clauses

Ví dụ 1: “Regulations that must be followed include wearing protective equipment and adhering to safety protocols.”
→ Phân tích: Defining relative clause modifying “regulations”

Ví dụ 2: “Employees who need to upgrade their skills can access professional development programs which should be subsidized by employers.”
→ Band 8+ features: Multiple relative clauses, interconnected ideas, stakeholder responsibility

Ví dụ 3: “The measures that governments ought to implement, such as carbon taxes and renewable energy subsidies, require political will and public support.”
→ Phân tích: Non-defining clause with examples, sophisticated vocabulary

Cụm Từ Nâng Cao (Collocations)

Academic Collocations với Deontic Modals

Collocation	Ví dụ	Band Level	Giải thích
must address the issue	Policymakers must address the issue of income inequality through progressive taxation.	7-8	Formal, problem-focused
should prioritize	Governments should prioritize education funding over military spending.	7	Clear preference/recommendation
need to acknowledge	Society needs to acknowledge that mental health is as important as physical health.	8	Recognition of truth/reality
ought to recognize	We ought to recognize the contribution of frontline workers during the pandemic.	8	Moral/ethical obligation
must take responsibility	Corporations must take responsibility for their environmental impact.	7-8	Accountability focus
have a duty to	Citizens have a duty to participate in democratic processes.	8	Strong moral obligation
should be obliged to	Companies should be obliged to disclose their carbon emissions publicly.	8+	Legal/formal requirement
need to ensure that	Educators need to ensure that all students have equal access to resources.	7-8	Guaranteeing outcomes
must strive to	Nations must strive to achieve sustainable development goals by 2030.	8	Effort + goal-oriented
ought to bear in mind	Policymakers ought to bear in mind the long-term consequences of their decisions.	8-9	Thoughtful consideration
should refrain from	Individuals should refrain from making judgments based on stereotypes.	8	Formal negative advice
need to cultivate	Schools need to cultivate critical thinking skills in students.	8+	Developmental focus

Sentence Starters với Deontic Modals (Band 8-9)

“It is imperative that…” + subject + base verb (subjunctive mood)

• “It is imperative that governments implement comprehensive climate policies without delay.”
• Meaning: Rất cần thiết, không thể thiếu
• Band 9 feature: Subjunctive mood không có ‘s’ ở ngôi thứ 3

“There is an urgent need to…”

• “There is an urgent need to reform the education system to meet 21st-century demands.”
• Meaning: Có sự cần thiết khẩn cấp

“It is essential that…” + subject + base verb

• “It is essential that students develop digital literacy skills in the modern era.”
• Band 8+: Formal academic expression

“Under no circumstances should…” (Inversion)

• “Under no circumstances should individuals compromise their ethical principles for financial gain.”
• Band 9 feature: Inversion for emphasis

Câu Phức & Ghép

Multi-clause Sentences với Multiple Modals

Ví dụ 1 (Band 8):
“While individuals must take personal responsibility for their health through regular exercise and balanced diets, governments should create environments that facilitate healthy choices, and healthcare systems need to provide accessible preventive services rather than focusing solely on treating diseases.”

→ Phân tích:

• Three independent clauses với three different modals
• Contrast structure (While… governments… and…)
• Complex reasoning: individual + government + system responsibilities
• Sophisticated transition: “rather than” for contrast

Ví dụ 2 (Band 9):
“Given that climate change poses an existential threat, nations must collaborate on emission reduction targets, corporations ought to transition to sustainable business models, and individuals should modify their consumption patterns; however, these efforts will only succeed if policymakers have the courage to implement unpopular but necessary measures.”

→ Phân tích:

• Four modals expressing different stakeholder obligations
• Causal reasoning: Given that…
• Semicolon usage for complex sentence
• Conditional clause at end adding nuance
• Advanced vocabulary: existential threat, transition, consumption patterns

Ví dụ 3 (Band 9):
“Although technology companies must prioritize user privacy by implementing robust security measures, they should not be solely responsible for protecting data; rather, governments need to establish comprehensive regulations, users ought to educate themselves about digital risks, and educational institutions must incorporate cybersecurity awareness into their curricula.”

→ Phân tích:

• Five different modals across multiple clauses
• Concession (Although) + contrast (rather)
• Multiple stakeholders addressed
• Parallel structure: governments… users… institutions…
• Topic-specific terminology: robust security measures, comprehensive regulations, cybersecurity awareness

Cấu trúc câu nâng cao kết hợp Deontic Modals trong IELTS Writing Task 2 Band 8-9

So Sánh Với Cấu Trúc Tương Tự

Must vs Have To – Sự Khác Biệt Quan Trọng

Tiêu chí	Must	Have To
Nguồn gốc nghĩa vụ	Quy định tuyệt đối, luật pháp, hoặc quan điểm cá nhân mạnh	Hoàn cảnh bên ngoài, quy tắc tổ chức, yêu cầu thực tế
Tone	Rất mạnh mẽ, authoritative	Trung lập, objective
Văn nói	Ít dùng (trừ khi muốn nhấn mạnh)	Phổ biến, tự nhiên
Văn viết Academic	Phổ biến trong formal writing	Cũng phổ biến
Dạng quá khứ	❌ Không có (dùng had to)	✅ had to
Dạng phủ định	mustn’t = cấm đoán	don’t have to = không cần
Ví dụ IELTS Speaking	“I believe teachers must inspire students, not just transfer knowledge.” (quan điểm cá nhân)	“I have to take the bus to work because I don’t own a car.” (hoàn cảnh)
Ví dụ IELTS Writing	“Governments must implement urgent measures to combat climate change.” (obligation mạnh)	“To remain competitive, companies have to adapt to technological changes.” (necessity logic)
Band score impact	Band 7-8 nếu dùng đúng context	Band 6-7 (basic competence)

Khi nào dùng Must:

• Viết Opinion Essay thể hiện quan điểm mạnh mẽ
• Nói về luật pháp, quy định bắt buộc tuyệt đối
• Đưa ra khuyến nghị quan trọng trong Problem-Solution essay

Khi nào dùng Have To:

• Mô tả thói quen, hoàn cảnh cá nhân trong Speaking
• Giải thích nguyên nhân bên ngoài
• Nói về quy định công ty, tổ chức

Ví dụ so sánh:

• “Students must respect their teachers.” (moral obligation – universal rule)
• “Students have to wear uniforms at my school.” (specific requirement – my school’s rule)

Should vs Ought To – Nuance Tinh Tế

Tiêu chí	Should	Ought To
Tần suất	Rất phổ biến	Ít dùng hơn
Register	Neutral – cả informal và formal	Formal hơn
Ngữ cảnh	Mọi tình huống	Moral/ethical advice đặc biệt
Văn nói	Tự nhiên	Hơi trang trọng
Văn viết	Phổ biến	Sophisticated choice
IELTS Speaking	Part 1, 2, 3 – tất cả	Part 3 (thảo luận ethical issues)
IELTS Writing	Task 2 – mọi essay type	Task 2 – thêm variation
Question form	Should I…? ✅	Ought I to…? (❌ hiếm, archaic)
Ví dụ	“Parents should teach children moral values.”	“Society ought to protect vulnerable groups.”
Band impact	Band 6-7 (competent)	Band 8 nếu dùng tự nhiên (shows range)

Khi nào dùng Should:

• Lời khuyên chung, phổ biến
• Speaking Part 1 – câu hỏi everyday advice
• Writing – general recommendations

Khi nào dùng Ought To:

• Thêm variety cho Band 8+
• Moral/ethical obligations
• Formal writing contexts
• Muốn sounds more authoritative

Ví dụ so sánh:

• “You should study hard for better grades.” (general advice)
• “As citizens, we ought to contribute to our community.” (moral duty)

Must Not vs Don’t Have To – Khác Biệt Quan Trọng Nhất

Tiêu chí	Must Not (Mustn’t)	Don’t Have To
Ý nghĩa	Cấm đoán, không được phép	Không cần thiết, không bắt buộc
Mức độ	Prohibition (nghiêm cấm)	Absence of obligation (tùy chọn)
Tương đương	= not allowed to, prohibited	= not necessary, optional
Ví dụ 1	“You mustn’t smoke in the hospital.” (cấm)	“You don’t have to smoke.” (không bắt buộc – vô lý) ❌
Ví dụ 2	“Students mustn’t cheat in exams.”	“Students don’t have to attend optional lectures.”
Ví dụ 3	“Drivers mustn’t exceed the speed limit.”	“You don’t have to drive if you prefer public transport.”
IELTS Speaking	“Children mustn’t be rude to adults.”	“Parents don’t have to help with homework, but it’s beneficial.”
IELTS Writing	“Governments must not ignore environmental concerns.”	“Companies don’t have to provide free meals, though it improves morale.”
Lỗi phổ biến	❌ “You mustn’t go” khi muốn nói “không cần đi”	✅ Phải dùng: “You don’t have to go”

LƯU Ý QUAN TRỌNG CHO HỌC VIÊN VIỆT NAM:

Đây là lỗi phổ biến nhất! Nhiều học viên dùng mustn’t khi muốn nói “không cần phải” (don’t have to), dẫn đến sai nghĩa hoàn toàn.

Ví dụ sai thường gặp:

• ❌ “You mustn’t bring gifts to the party.”
  • (Nghĩa: Bạn không được mang quà = cấm)
• ✅ “You don’t have to bring gifts to the party.”
  • (Nghĩa: Bạn không cần mang quà = không bắt buộc)

Need To vs Should – Necessity vs Advice

Tiêu chí	Need To	Should
Bản chất	Sự cần thiết logic, thực tế	Lời khuyên, khuyến nghị
Mức độ	Stronger than should	Weaker, more flexible
Hậu quả nếu không làm	Có hậu quả thực tế rõ ràng	Có thể không có hậu quả nghiêm trọng
Ngữ cảnh	Practical necessity	Moral/advisable action
Ví dụ 1	“You need to study to pass the exam.” (necessity for result)	“You should study regularly for better understanding.” (advice)
Ví dụ 2	“Companies need to innovate to survive.” (business necessity)	“Companies should treat employees well.” (ethical advice)
IELTS Writing	Problem-solution: “Governments need to address unemployment.”	Opinion: “Children should spend time outdoors.”
Band score	Band 7+ với reasoning rõ ràng	Band 6-7 (basic advice)

Khi nào dùng Need To:

• Có clear cause-effect relationship
• Practical solutions trong Problem-Solution essays
• Khi failure to act có specific negative consequences

Khi nào dùng Should:

• General recommendations
• Moral/ethical advice
• When suggesting best practices without dire consequences

Lỗi Thường Gặp & Cách Sửa

Lỗi 1: Nhầm Lẫn Mustn’t và Don’t Have To

❌ SAI:
“You mustn’t worry about the test; it’s not very difficult.”

✅ ĐÚNG:
“You don’t have to worry about the test; it’s not very difficult.”

Giải thích:
Đây là lỗi phổ biến nhất của học viên Việt Nam. “Mustn’t” nghĩa là “cấm, không được phép” (prohibition), trong khi “don’t have to” nghĩa là “không cần thiết” (no obligation). Câu sai ở trên có nghĩa là “bạn không được lo lắng” (cấm lo lắng – không hợp lý), trong khi ý muốn nói là “bạn không cần lo lắng” (không bắt buộc phải lo).

Lưu ý:

• Mustn’t = prohibition, ban (cấm đoán)
  • “You mustn’t smoke here.” (Cấm hút thuốc)
• Don’t have to = not necessary (không cần thiết)
  • “You don’t have to come if you’re busy.” (Không bắt buộc đến)

Ví dụ thêm:

• ❌ “Students mustn’t do homework tonight.” (Học sinh không được làm bài = cấm làm)
• ✅ “Students don’t have to do homework tonight.” (Không bắt buộc làm bài)

Lỗi 2: Sử Dụng Must Cho Quá Khứ

❌ SAI:
“Yesterday, I must finish my report before 5 PM.”

✅ ĐÚNG:
“Yesterday, I had to finish my report before 5 PM.”

Giải thích:
“Must” không có dạng quá khứ. Khi muốn diễn tả nghĩa vụ trong quá khứ, PHẢI dùng “had to”. Đây là quy tắc ngữ pháp cố định, không có ngoại lệ.

Quy tắc:

• Present: must / have to → “I must go now.” / “I have to go now.”
• Past: had to (ONLY) → “I had to go yesterday.”
• Future: will have to → “I will have to go tomorrow.”

Ví dụ thêm:

• ❌ “Last week, students must attend a special lecture.”
• ✅ “Last week, students had to attend a special lecture.”

IELTS Speaking Part 2 example:
“When I was in high school, I had to wake up at 5:30 AM every day because my school was far from home. At that time, all students had to wear uniforms, and we had to participate in morning exercises before classes started.”

Lỗi 3: Thêm “To” Sau Should/Must

❌ SAI:
“Students should to study harder for better results.”

✅ ĐÚNG:
“Students should study harder for better results.”

Giải thích:
Modal verbs (must, should, can, may, might, would, could) LUÔN theo sau bởi động từ nguyên thể KHÔNG có “to” (bare infinitive). Đây là lỗi cơ bản nhưng rất phổ biến do ảnh hưởng của các cấu trúc khác như “want to”, “need to”, “have to”.

Quy tắc:

• Modal + bare infinitive: should study, must go, can speak
• Không phải modal + to infinitive: need to study, have to go, want to speak, ought to do

Các lỗi tương tự:

• ❌ “You must to follow the rules.”
  • ✅ “You must follow the rules.”
• ❌ “She can to speak three languages.”
  • ✅ “She can speak three languages.”
• ❌ “We should to protect the environment.”
  • ✅ “We should protect the environment.”

Lưu ý đặc biệt:
“Ought to” là NGOẠI LỆ duy nhất – nó CẦN “to”:

• ✅ “We ought to help the elderly.”

Lỗi 4: Chia Động Từ Modal Theo Ngôi

❌ SAI:
“She musts complete the assignment by Friday.”

✅ ĐÚNG:
“She must complete the assignment by Friday.”

Giải thích:
Modal verbs KHÔNG BAO GIỜ thêm “s/es” ở ngôi thứ 3 số ít. Đây là đặc điểm cố định của modal verbs – chúng không chia theo ngôi hay số.

Quy tắc:

• I/You/We/They/He/She/It must (giống nhau tất cả)
• I/You/We/They/He/She/It should (không đổi)
• I/You/We/They/He/She/It can (không có “cans”)

Các lỗi tương tự:

• ❌ “He shoulds apologize.”
  • ✅ “He should apologize.”
• ❌ “The company cans offer flexible hours.”
  • ✅ “The company can offer flexible hours.”

Lưu ý:
“Have to” KHÔNG phải modal verb thuần túy, nên nó VẪN chia theo ngôi:

• I/You/We/They have to
• He/She/It has to ✅

Lỗi 5: Dùng Sai Must Trong Câu Hỏi

❌ SAI (ít phổ biến):
“Must I attend the meeting tomorrow?”

✅ TỰ NHIÊN HƠN:
“Do I have to attend the meeting tomorrow?”

Giải thích:
Mặc dù “Must I…?” đúng ngữ pháp, nhưng nó rất formal và hiếm khi dùng trong tiếng Anh hiện đại, đặc biệt trong văn nói. Người bản xứ thường dùng “Do I have to…?” hoặc “Do I need to…?” để hỏi về nghĩa vụ.

Quy tắc cho câu hỏi:

• Formal (hiếm): Must I…? / Should I…?
• Natural (phổ biến): Do I have to…? / Do I need to…? / Should I…?

Ví dụ IELTS Speaking:

• ❌ “Must students wear uniforms in your country?” (quá formal, không tự nhiên)
• ✅ “Do students have to wear uniforms in your country?” (natural)
• ✅ “Are students required to wear uniforms?” (academic alternative)

Các câu hỏi tự nhiên:

• “Do I have to submit it today?” (Tôi có cần nộp hôm nay không?)
• “Do we need to bring anything?” (Chúng ta có cần mang gì không?)
• “Does she have to attend?” (Cô ấy có bắt buộc tham dự không?)

Lỗi 6: Dùng Should Have Done Sai Ngữ Cảnh

❌ SAI:
“You should have go to the party last night.” (sai cấu trúc)
“I think the government should have build more schools.” (sai về thời gian – nếu đang nói về kế hoạch tương lai)

✅ ĐÚNG:
“You should have gone to the party last night.” (regret về quá khứ)
“I think the government should build more schools.” (recommendation cho hiện tại/tương lai)

Giải thích:
“Should have + past participle” chỉ dùng cho việc đã không xảy ra trong quá khứ và thể hiện regret (tiếc nuối) hoặc criticism (phê bình). Không dùng cấu trúc này cho recommendations về hiện tại hoặc tương lai.

Cấu trúc đúng:

• Past regret/criticism: should have + past participle
  • “The government should have acted sooner.” (đáng lẽ nên hành động sớm hơn – nhưng đã không)
• Present/Future advice: should + base verb
  • “The government should act now.” (nên hành động bây giờ)

Ví dụ IELTS Writing:
✅ “In retrospect, governments should have invested in renewable energy decades ago to prevent the current climate crisis.” (past criticism)
✅ “Moving forward, governments should invest heavily in renewable energy to mitigate climate change.” (future recommendation)

Lỗi 7: Nhầm Lẫn Be Supposed To và Should

❌ SAI (về ý nghĩa):
“You are supposed to exercise regularly if you want to be healthy.”

✅ ĐÚNG:
“You should exercise regularly if you want to be healthy.”

Giải thích:
“Be supposed to” diễn tả kỳ vọng hoặc quy định có sẵn (expectation/rule), thường hàm ý reality có thể khác. “Should” diễn tả lời khuyên chung, recommendation. Câu ví dụ sai vì exercise không phải là quy định hay kỳ vọng mà là lời khuyên sức khỏe.

Phân biệt:

• Be supposed to: rules, regulations, expectations (có thể không tuân thủ)
  • “Students are supposed to arrive by 8 AM, but many come late.” (quy định + thực tế khác)
• Should: advice, recommendations (general wisdom)
  • “Students should arrive on time to avoid missing important information.” (lời khuyên)

Ví dụ thêm:

• ✅ “The meeting is supposed to start at 3 PM.” (scheduled expectation)
• ✅ “You should arrive 10 minutes early for meetings.” (advice)

Những lỗi sai phổ biến nhất khi sử dụng Deontic Modals trong IELTS của học viên Việt Nam

Top 5 Mistakes Vietnamese Learners Make

1. Confusion between Mustn’t and Don’t Have To

• Problem: 90% học viên Việt sử dụng “mustn’t” khi muốn nói “không cần thiết”
• Root cause: Dịch trực tiếp từ “không phải” → “must not”
• Solution: Nhớ rằng mustn’t = prohibition (cấm), don’t have to = no necessity (không bắt buộc)
• Practice: Làm bài tập phân biệt hai cấu trúc này thường xuyên

2. Using Must for Past Events

• Problem: Dùng “must” cho sự kiện quá khứ vì không biết must không có past form
• Root cause: Không nắm vững đặc điểm của modal verbs
• Solution: Học thuộc: Past obligation = had to (ONLY)
• Practice: Khi kể về quá khứ, luôn check xem đã dùng “had to” chưa

3. Adding “To” After Modals

• Problem: Viết “should to”, “must to” do ảnh hưởng của “have to”, “need to”
• Root cause: Confusion giữa modal verbs và semi-modals
• Solution: Nhớ công thức: Modal + BARE infinitive (no “to”)
• Exception: Chỉ có “ought to” và “have to” có “to”

4. Over-using Must in Speaking

• Problem: Lạm dụng “must” khiến giọng điệu quá authoritative và không tự nhiên
• Root cause: Học quá nhiều grammar rules, thiếu exposure với authentic language
• Solution: Dùng “have to” cho daily obligations, “should” cho advice, chỉ dùng “must” khi thật sự cần emphasize
• Practice: Nghe podcasts/watch videos để observe natural usage

5. Wrong Modal for Context

• Problem: Dùng “should” khi cần “must”, hoặc “must” khi nên dùng “need to”
• Root cause: Không hiểu sự khác biệt về strength of obligation
• Solution: Học scale: must (strongest) → need to → should (weakest for obligation)
• Practice: Phân tích sample answers Band 8-9 để thấy modals được dùng trong contexts nào

Bài Tập Thực Hành

Bài Tập 1: Điền Modal Verb Phù Hợp

Điền must, mustn’t, have to, don’t have to, should, shouldn’t, need to, hoặc ought to vào chỗ trống:

1. Students __ wear uniforms at my school. It’s a strict rule.
2. You __ worry about the presentation; you’ve prepared well. (không cần lo lắng)
3. To pass IELTS 7.0, candidates __ demonstrate a wide range of vocabulary and grammar.
4. Children __ use mobile phones during class time. It’s prohibited.
5. Employees __ work on Sundays unless there’s an emergency. (không bắt buộc)
6. If you want to improve your speaking, you __ practice daily with native speakers.
7. Governments __ take immediate action to combat climate change, or the consequences will be catastrophic.
8. Teenagers __ spend at least 8 hours sleeping for optimal health.
9. You __ submit your assignment by Friday, but earlier submission would be appreciated. (không bắt buộc vào Friday)
10. Drivers __ exceed the speed limit in residential areas.
11. People __ respect cultural differences when traveling abroad.
12. I __ attend the meeting yesterday, so I worked late to prepare. (quá khứ)
13. Companies __ provide maternity leave to employees. It’s the law.
14. Students __ memorize everything; understanding concepts is more important.
15. To achieve sustainable development, nations __ work together rather than competing.

Bài Tập 2: Tìm Và Sửa Lỗi

Mỗi câu sau có một lỗi sai. Tìm và sửa lỗi:

1. Students musts complete their homework before class. [❌]
2. You mustn’t bring an umbrella; it’s not going to rain. [❌]
3. Yesterday, I must attend a training session at work. [❌]
4. Children should to learn a foreign language at an early age. [❌]
5. Do students must wear uniforms in your school? [❌]
6. She don’t have to work on weekends, so she usually travels. [❌]
7. Governments must to implement stricter environmental regulations. [❌]
8. You are supposed study at least 3 hours daily for IELTS preparation. [❌]
9. Teachers ought spend more time understanding students’ individual needs. [❌]
10. He should have went to the doctor when he first felt sick. [❌]
11. Employees are suppose to clock in by 8:30 AM every morning. [❌]
12. We mustn’t buy tickets in advance; the event is free. [❌]
13. Students needs to develop critical thinking skills for academic success. [❌]
14. You had not to wait for me yesterday; I could have taken a taxi. [❌]
15. People should have protect the environment decades ago. [❌]

Bài Tập 3: Viết Câu Hoàn Chỉnh

Viết câu hoàn chỉnh sử dụng từ gợi ý và modal verb phù hợp:

1. (governments / take action / climate change / urgently)
   → Your answer: ___

2. (students / not / cheat / exams / because / dishonest)
   → Your answer: ___

3. (employees / attend / training sessions / improve skills)
   → Your answer: ___

4. (children / spend / more time / outdoor activities)
   → Your answer: ___

5. (people / not / judge others / based on / appearance)
   → Your answer: ___

6. (companies / provide / safe / working environment / staff)
   → Your answer: ___

7. (yesterday / I / finish / report / before deadline)
   → Your answer: ___

8. (to achieve success / individuals / work hard / stay focused)
   → Your answer: ___

9. (visitors / not / take photos / inside the museum / prohibited)
   → Your answer: ___

10. (teachers / encourage / students / think critically)
    → Your answer: ___

Bài Tập 4: Chuyển Đổi Câu

Viết lại câu với modal verb được gợi ý, giữ nguyên ý nghĩa:

1. It’s necessary for students to attend at least 80% of classes.
   → (must) Students _____

2. It’s not necessary to book tickets in advance.
   → (don’t have to) You _____

3. It’s prohibited to smoke in public buildings.
   → (mustn’t) People _____

4. I recommend that you practice speaking English daily.
   → (should) You _____

5. It was necessary for me to wake up early yesterday.
   → (had to) I _____

6. Taking photographs is not allowed in the museum.
   → (mustn’t) Visitors _____

7. It’s advisable for governments to invest in education.
   → (ought to) Governments _____

8. It’s essential for employees to maintain confidentiality.
   → (must) Employees _____

9. Attending the optional workshop is not compulsory.
   → (don’t have to) Students _____

10. It’s important for children to learn moral values at home.
    → (should) Children _____

Bài Tập 5: IELTS Speaking Practice

Trả lời các câu hỏi sau sử dụng ít nhất 2 modal verbs khác nhau trong mỗi câu trả lời:

Part 1 Questions:

1. Do you have to wake up early every day? Why?
2. What rules must students follow in schools in your country?
3. Should children learn a foreign language at school? Why?

Part 3 Questions:

4. What responsibilities should parents have in educating their children?
5. Must governments do more to protect the environment? How?
6. Do you think people ought to help their elderly neighbors? Why?

Ghi âm hoặc viết ra câu trả lời của bạn, sau đó:

• Đếm số modal verbs sử dụng
• Check xem đã dùng đúng form chưa
• Xem có variety không (nhiều modals khác nhau)

Bài Tập 6: IELTS Writing Task 2 Practice

Topic: Many people believe that parents should teach children how to be good members of society. Others believe that school is the place to learn this. Discuss both views and give your opinion.

Yêu cầu: Viết 1 body paragraph (khoảng 120-150 từ) thảo luận về một trong hai quan điểm. Sử dụng ít nhất 5 modal verbs khác nhau một cách tự nhiên.

Checklist sau khi viết:

• [ ] Đã sử dụng ít nhất 5 modal verbs khác nhau
• [ ] Tất cả modal verbs đều đúng form
• [ ] Ý nghĩa các modals phù hợp với context
• [ ] Có variety (không chỉ dùng should)
• [ ] Topic sentence rõ ràng
• [ ] Supporting ideas có examples
• [ ] Concluding sentence

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Đáp Án Chi Tiết

Đáp Án Bài Tập 1:

1. must / have to (quy định bắt buộc)
2. don’t have to (không cần thiết – no obligation)
3. must / need to (yêu cầu để pass)
4. mustn’t (cấm đoán – prohibition)
5. don’t have to (không bắt buộc)
6. should / need to / ought to (lời khuyên logic)
7. must (nghĩa vụ urgent và mạnh)
8. should / ought to (khuyến nghị sức khỏe)
9. don’t have to (không bắt buộc Friday)
10. mustn’t (cấm vượt tốc độ)
11. should / ought to / must (nghĩa vụ đạo đức)
12. had to (quá khứ obligation)
13. must / have to (luật pháp)
14. don’t have to / shouldn’t (không cần thiết memorize)
15. must / need to (necessity cho sustainable development)

Giải thích chi tiết:

• Câu 2 & 5: Don’t have to = không bắt buộc (no obligation), khác hẳn với mustn’t = cấm
• Câu 4 & 10: Mustn’t = prohibition, used for rules/laws
• Câu 12: Must không có quá khứ, phải dùng had to
• Câu 7: Must (không phải should) vì urgency và serious consequences
• Câu 14: Don’t have to phù hợp hơn shouldn’t vì emphasize “không cần thiết” chứ không phải “không nên”

Đáp Án Bài Tập 2:

1. ❌ “musts” → ✅ must

   • Giải thích: Modal verbs không chia theo ngôi

2. ❌ “mustn’t bring” → ✅ don’t have to bring

   • Giải thích: Mustn’t = cấm, nhưng ý câu là “không cần mang” = don’t have to

3. ❌ “I must attend” → ✅ I had to attend

   • Giải thích: Must không có quá khứ, dùng had to cho past obligation

4. ❌ “should to learn” → ✅ should learn

   • Giải thích: Modal + bare infinitive (no “to”)

5. ❌ “Do students must” → ✅ Must students / Do students have to

   • Giải thích: Question form: “Must + subject” hoặc “Do + subject + have to”

6. ❌ “She don’t have to” → ✅ She doesn’t have to

   • Giải thích: Ngôi thứ 3 số ít dùng doesn’t (have to không phải modal thuần túy)

7. ❌ “must to implement” → ✅ must implement

   • Giải thích: Modal + bare infinitive

8. ❌ “are supposed study” → ✅ are supposed to study

   • Giải thích: Be supposed TO + verb (luôn có “to”)

9. ❌ “ought spend” → ✅ ought to spend

   • Giải thích: Ought TO + verb (luôn có “to”)

10. ❌ “should have went” → ✅ should have gone

    • Giải thích: Should have + PAST PARTICIPLE (gone, not went)

11. ❌ “are suppose to” → ✅ are supposed to

    • Giải thích: Be supposed (past participle), not “suppose”

12. ❌ “We mustn’t buy” → ✅ We don’t have to buy

    • Giải thích: Mustn’t = cấm mua (vô lý), ý là “không cần mua” = don’t have to

13. ❌ “Students needs to” → ✅ Students need to

    • Giải thích: Students (số nhiều) + need (không có “s”)

14. ❌ “had not to wait” → ✅ didn’t have to wait

    • Giải thích: Past negative của have to là didn’t have to

15. ❌ “should have protect” → ✅ should have protected

    • Giải thích: Should have + PAST PARTICIPLE

Đáp Án Bài Tập 3:

1. Governments must take urgent action on climate change. / Governments need to address climate change urgently.

2. Students mustn’t cheat in exams because it’s dishonest. / Students shouldn’t cheat in exams because it’s dishonest and undermines learning.

3. Employees should attend training sessions to improve their skills. / Employees need to participate in training sessions to enhance their professional skills.

4. Children should spend more time on outdoor activities. / Children ought to engage in more outdoor activities for their physical and mental health.

5. People shouldn’t judge others based on their appearance. / People mustn’t discriminate against others based on appearance.

6. Companies must provide a safe working environment for their staff. / Employers have to ensure workplace safety for all employees.

7. Yesterday, I had to finish my report before the deadline. / I had to complete the report yesterday to meet the deadline.

8. To achieve success, individuals need to work hard and stay focused. / To succeed, people must work diligently and maintain focus on their goals.

9. Visitors mustn’t take photos inside the museum as it’s prohibited. / Photography is not allowed inside the museum, so visitors mustn’t take pictures.

10. Teachers should encourage students to think critically. / Teachers ought to foster critical thinking skills in their students.

Band 8+ versions (với advanced structures):

1. “To combat the devastating effects of global warming, governments must implement comprehensive environmental policies and need to enforce strict regulations on carbon emissions.”

2. “In order to remain competitive in the job market, employees should attend regular training sessions, and companies ought to invest in professional development programs.”

3. “To achieve long-term success, individuals must cultivate a strong work ethic and need to develop resilience in the face of challenges.”

Đáp Án Bài Tập 4:

1. Students must attend at least 80% of classes.

2. You don’t have to book tickets in advance.

3. People mustn’t smoke in public buildings.

4. You should practice speaking English daily.

5. I had to wake up early yesterday.

6. Visitors mustn’t take photographs in the museum.

7. Governments ought to invest in education.

8. Employees must maintain confidentiality.

9. Students don’t have to attend the optional workshop.

10. Children should learn moral values at home.

Đáp Án Bài Tập 5:

Sample Answers (Band 7-8):

1. Do you have to wake up early every day?

“Yes, I have to wake up around 6 AM on weekdays because I need to commute to my office, which is about an hour away. However, I don’t have to wake up early on weekends, so I usually sleep in until 9 or 10. I think everyone should get enough sleep, so I try to go to bed early on work nights.”

→ Analysis: 4 modals used naturally (have to, need to, don’t have to, should), good variety, natural flow.

2. What rules must students follow in schools?

“Well, there are quite a few regulations. Students must wear uniforms and have to arrive before 7:30 AM. They mustn’t use mobile phones during lessons, and they should respect their teachers and classmates. I think these rules are reasonable because students need to learn discipline from a young age.”

→ Analysis: 5 modals (must, have to, mustn’t, should, need to), shows clear understanding of obligation levels.

4. What responsibilities should parents have? (Part 3)

“I believe parents must provide a loving and stable environment for their children’s development. They should teach moral values and social skills rather than just focusing on academic achievement. Parents also need to spend quality time with their children and ought to be good role models through their own behavior. However, they shouldn’t be overprotective or controlling, as children need to develop independence. Ultimately, parents have a responsibility to prepare their children for adult life while allowing them space to grow.”

→ Analysis: 7 modals, sophisticated argumentation, balanced view, Band 8+ features.

6. Should people help elderly neighbors?

“Absolutely. I think it’s a moral obligation – people should definitely look after elderly neighbors, especially those living alone. In traditional societies, younger generations were supposed to care for the elderly, but modern lifestyles have changed this. Still, we mustn’t abandon this value. Even small gestures make a difference – we don’t have to do anything grand; simple acts like checking on them regularly or helping with shopping can make a huge difference. I believe communities need to foster this sense of mutual support, and governments ought to provide resources for elderly care as well. However, we shouldn’t rely entirely on government; individual action is crucial.”

→ Analysis: 8 modals, multiple perspectives (tradition vs modernity, individual vs government), complex reasoning, Band 9 features.

Đáp Án Bài Tập 6:

Sample Paragraph (Band 8):

“On one hand, proponents of school-based moral education argue that educational institutions must play a central role in teaching social values because they provide structured curricula designed by professionals. Schools can ensure all children receive consistent guidance regardless of their family background, which is crucial since not all parents have the knowledge or skills required for effective moral instruction. Teachers are trained to address diverse learning needs and can present ethical concepts systematically through age-appropriate activities. Moreover, schools provide environments where students need to interact with peers from various backgrounds, allowing them to practice cooperation, conflict resolution, and respect for differences – skills that naturally emerge in classroom settings. Therefore, advocates believe that schools should assume greater responsibility for developing well-rounded citizens, and governments ought to invest in comprehensive character education programs.”

→ Analysis:

• Modals used: must, have, are trained to, can, need to, should, ought to (7 different forms)
• Structure: Clear topic sentence, supporting points, logical flow
• Vocabulary: proponents, structured curricula, consistent guidance, comprehensive
• Grammar: Complex sentences, relative clauses, reason clauses
• Band: 8.0 (variety, accuracy, coherence, task response)

Kết Luận

Deontic Modals for Obligation là một trong những cấu trúc ngữ pháp quan trọng nhất để đạt Band 7-9 trong kỳ thi IELTS. Việc sử dụng thành thạo các động từ khiếm khuyết này không chỉ giúp bạn diễn đạt chính xác các mức độ nghĩa vụ khác nhau mà còn thể hiện sự tinh tế trong tư duy và khả năng sử dụng ngôn ngữ một cách tự nhiên.

Những điểm chính cần nhớ:

1. Must – Nghĩa vụ mạnh nhất, dùng cho luật pháp, quy định bắt buộc, hoặc quan điểm cá nhân mạnh mẽ. Không có dạng quá khứ (dùng had to).

2. Have to – Nghĩa vụ do hoàn cảnh bên ngoài, tự nhiên hơn trong văn nói, có thể chia theo thời.

3. Should / Ought to – Lời khuyên, khuyến nghị; ought to trang trọng hơn và phù hợp cho Band 8+.

4. Need to – Sự cần thiết logic, thực tế; mạnh hơn should nhưng yếu hơn must.

5. Be supposed to – Kỳ vọng, quy định (có thể không thực hiện); thường hàm ý reality khác expectation.

6. Mustn’t vs Don’t have to – Sự khác biệt QUAN TRỌNG NHẤT: mustn’t = cấm đoán; don’t have to = không cần thiết.

Lộ trình luyện tập:

Tuần 1-2: Nắm vững công thức cơ bản, phân biệt rõ must/have to, should/ought to, mustn’t/don’t have to. Làm bài tập điền từ và sửa lỗi.

Tuần 3-4: Thực hành Speaking Part 1 với các câu hỏi về rules, obligations, daily routines. Tập sử dụng ít nhất 2-3 modals khác nhau trong mỗi câu trả lời.

Tuần 5-6: Luyện Writing Task 2 – tích hợp modals vào các dạng essay (Opinion, Problem-Solution, Discussion). Focus vào variety và accuracy.

Tuần 7-8: Practice Speaking Part 3 với sophisticated reasoning, multiple perspectives. Kết hợp modals với complex structures (conditionals, relative clauses, passive voice).

Đề Luyện Tập

Speaking Topics:

1. Describe a rule that you think is important (Part 2)

   • What the rule is
   • Where this rule applies
   • How people follow it
   • Why you think it’s important
   • Yêu cầu: Sử dụng must, have to, should, mustn’t, ought to ít nhất 5 lần

2. Talk about changes in education in your country (Part 2/3)

   • What changes have occurred
   • What changes should be made
   • What responsibilities teachers/parents/students have
   • Yêu cầu: Demonstrate variety với 6+ different modals

3. Discuss environmental responsibilities (Part 3)

   • What must governments do?
   • What should individuals do?
   • What don’t people have to do but could help?
   • Yêu cầu: Multiple perspectives, Band 8-9 level argumentation

Writing Task 2 Topics:

1. Opinion Essay: “Some people believe that children should be required to help with household tasks as soon as they are able. Others believe childhood should be a time for play and learning. Discuss both views and give your opinion.”

   • Yêu cầu: Sử dụng must, should, have to, need to, ought to, don’t have to trong cả body paragraphs và conclusion

2. Problem-Solution Essay: “Traffic congestion is a serious problem in many cities. What are the causes of this issue, and what measures should be taken to solve it?”

   • Yêu cầu: Problems paragraph với modals analyzing causes; Solutions paragraph với must, should, need to, ought to đưa ra giải pháp cụ thể

3. Discussion Essay: “Some believe that university students should be required to attend classes. Others believe attendance should be optional. Discuss both views and give your opinion.”

   • Yêu cầu: Balanced discussion với variety of obligation modals, sophisticated reasoning

4. Advantage-Disadvantage Essay: “In many countries, people have to pay for medical treatment. What are the advantages and disadvantages of this system?”

   • Yêu cầu: Accurate use của have to vs must vs should trong discussing policies

Self-Study Resources:

• Podcasts: Listen to BBC Sounds, TED Talks – note down modals used in different contexts
• YouTube: Watch IELTS examiner sample answers – analyze modal usage
• Reading: Cambridge IELTS 10-19 – highlight modals in passages
• Writing practice: Keep a journal noting obligations, advice, rules in your daily life using various modals

Assessment Criteria:

Để đạt Band 7+:

• ✅ Sử dụng ít nhất 4-5 modals khác nhau trong Speaking Part 2/3
• ✅ Không có lỗi cơ bản (must → had to, mustn’t vs don’t have to)
• ✅ Natural flow, không overuse một modal duy nhất

Để đạt Band 8+:

• ✅ Variety: 6+ modals including ought to, be supposed to, need to
• ✅ Complex structures: modals + passive, modals + perfect infinitive
• ✅ Sophisticated reasoning với appropriate obligation levels
• ✅ Zero basic errors, natural and fluent usage

Để đạt Band 9:

• ✅ Full range: tất cả modals used appropriately
• ✅ Advanced combinations: modals in conditionals, with inversion, in relative clauses
• ✅ Nuanced understanding: chọn modal perfectly phù hợp với từng context
• ✅ Native-like fluency và naturalness

Chúc bạn học tốt và đạt điểm cao trong kỳ thi IELTS! Hãy nhớ rằng việc thành thạo Deontic Modals không chỉ giúp bạn trong thi cử mà còn là kỹ năng giao tiếp tiếng Anh quan trọng trong học tập và công việc sau này.