What's the difference between 'must' and 'have to'?

'Must' usually expresses personal obligation (the speaker feels it's necessary). 'Have to' expresses external obligation (rules, laws, or someone else's authority).

When do I use 'should'?

Use 'should' to give advice or say what is the right thing to do. It is less strong than 'must' or 'have to'.

What is the negative form of 'must'?

The negative is 'mustn't', which means prohibition (not allowed).

How do I say something is not necessary?

Use 'don't have to' or 'doesn't have to'. Example: 'You don't have to wear a suit.'

What is the most common mistake with modals of obligation?

Using 'to' after a modal (e.g., 'must to go' instead of 'must go'), or confusing 'mustn't' (prohibition) with 'don't have to' (no necessity).

How do I change 'It is necessary to' into a modal?

Use 'must' or 'have to'. Example: 'It is necessary to arrive on time' → 'You must/have to arrive on time'.

Can I ask about specific rules?

Yes, ask about anything you're unsure about using modals like 'Do I have to...?' or 'Must I...?'.

How will the AI check my modals?

The AI will check if you used the correct modal for the type of obligation (personal vs external, prohibition vs lack of necessity, advice).

Master Modals of Obligation: Must, Have to, Should

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Practice Questions & Answers

All B1 questions for “Master Modals of Obligation: Must, Have to, Should – B1 Practice”, each with the correct answer and a short explanation. Try the interactive exercises above, then check your answers here.

Modals of Obligation: Choose the Correct Modal

1. You _____ wear a seatbelt in the car. It's the law.
- A. must
- B. have to ✓
- C. should
- D. can
Answer: have to
External obligation (law) → 'have to'.
2. I _____ remember to call my mum. It's her birthday.
- A. must ✓
- B. have to
- C. should
- D. might
Answer: must
Personal obligation → 'must'.
3. You _____ smoke in the hospital. It's prohibited.
- A. mustn't ✓
- B. don't have to
- C. shouldn't
- D. can't
Answer: mustn't
Prohibition → 'mustn't'.
4. You _____ wear a tie to the party. It's casual.
- A. mustn't
- B. don't have to ✓
- C. shouldn't
- D. can't
Answer: don't have to
Lack of necessity → 'don't have to'.
5. You _____ see a doctor. You look very ill.
- A. must
- B. have to
- C. should ✓
- D. can
Answer: should
Advice → 'should'.
6. We _____ be late for the meeting. The boss hates it.
- A. mustn't ✓
- B. don't have to
- C. shouldn't
- D. can't
Answer: mustn't
Strong prohibition → 'mustn't'.
7. She _____ work tomorrow. It's a public holiday.
- A. mustn't
- B. doesn't have to ✓
- C. shouldn't
- D. can't
Answer: doesn't have to
No necessity → 'doesn't have to'.
8. You _____ try the chocolate cake. It's delicious.
- A. must
- B. have to
- C. should ✓
- D. can
Answer: should
Recommendation → 'should'.

Modals of Obligation: First Day at the Office

1. _____ arrive by 9:00 AM. The doors lock automatically at 9:05. You _____ remember to bring your ID badge every day or security won't let you in. You _____ share your computer password with anyone, not even your manager. For lunch, you _____ eat in the cafeteria. There are many nice cafes nearby. However, you _____ try the sushi place on the corner. It's excellent. You _____ complete the online safety training by Friday. Finally, you _____ let me know if you have any questions at all. And you _____ come to the team coffee break at 10:30. It's a great way to meet everyone.
- A. mustn't
- B. don't have to
- C. shouldn't
- D. can't
Answer: have to, must, mustn't, don't have to, should, have to, must, should

Modals of Obligation: Spot the Mistake

1. Which option does not belong?
- A. You must to wear a helmet. ✓
- B. You must wear a helmet.
- C. You have to wear a helmet.
- D. You should wear a helmet.
Answer: You must to wear a helmet.
Never use 'to' after 'must'.
2. Which option does not belong?
- A. She doesn't have to work today.
- B. She hasn't to work today. ✓
- C. She mustn't work today.
- D. She should work today.
Answer: She hasn't to work today.
The correct negative for 'have to' is 'doesn't/don't have to', not 'hasn't to'.
3. Which option does not belong?
- A. You mustn't smoke here.
- B. You don't have to smoke here. ✓
- C. You shouldn't smoke here.
- D. You can't smoke here.
Answer: You don't have to smoke here.

Modals of Obligation: Rewrite the Rule

1. You _____
Answer: must wear a uniform.
2. You _____
Answer: mustn't use your phone.
3. You _____
Answer: don't have to bring food.
4. You _____
Answer: should rest.
5. Employees _____
Answer: have to sign in every morning.
6. I _____
Answer: must finish this report tonight.

Modals of Obligation: Speed Builder ⚡

1. Say something you personally feel you must do.
2. Mention a rule at your school or workplace.
3. State something that is prohibited.
4. Say something that is optional or not required.
5. Give a piece of health advice.
6. Say what someone ought to do.
7. Say something that is not necessary for a friend.
8. Express a strong obligation for a group.
9. Give negative advice.
10. Ask if someone has an external obligation.

Modals of Obligation: Write the Office Rules

1. Question 1

Master Modals of Obligation: Must, Have to, Should – B1 Practice

I _____ remember to call my mum. It's her birthday.

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Practice Questions & Answers

Modals of Obligation: Choose the Correct Modal

Modals of Obligation: First Day at the Office

Modals of Obligation: Spot the Mistake

Modals of Obligation: Rewrite the Rule

Modals of Obligation: Speed Builder ⚡

Modals of Obligation: Write the Office Rules

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