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Grammar

Modal Verbs: How and When to Use Them

Modal verbs are special verbs that help express ability, possibility, permission, obligation, advice, and more. They come before the main verb and do not change form. This essay explains how and when to use the main modal verbs in English. You will also learn the structure and meaning of each.

1. What Are Modal Verbs?

Modal verbs are: can, could, may, might, must, shall, should, will, would.

They are always followed by the base form of the verb (no ‘to’, no ‘-s’, no ‘-ed’).

Examples:
– She can speak French.
– You must finish this.
– I will call you later.

They do not use do/does/did in questions or negatives.

Examples:
– ✅ Should I go? ❌ Do should I go?
– ✅ He can’t swim. ❌ He doesn’t can swim.

2. Can / Could

Can:
– Ability (present/future): I can swim.
– Permission (informal): Can I leave early?
– Possibility: It can get cold here.

Could:
– Past ability: I could read when I was four.
– Polite permission: Could I borrow your pen?
– Possibility (less certain): It could rain later.

3. May / Might

May:
– Permission (formal): May I come in?
– Possibility: It may snow tonight.

Might:
– Possibility (less certain): He might be late.

Note: Might is often less certain than may.

4. Must / Have to

Must:
– Strong obligation: You must wear a seatbelt.
– Logical conclusion: He must be tired.

Have to:
– Obligation (external rules): I have to work on Monday.

Difference:
– Must: internal/speaker-driven.
– Have to: external/rule-driven.

Examples:
– You must stop (I say so).
– You have to stop (the law says so).

Negative forms:
– Must not = prohibition: You must not smoke here.
– Don’t have to = no obligation: You don’t have to come.

5. Shall / Should

Shall:
– Offers or suggestions (formal): Shall we go?

Should:
– Advice: You should see a doctor.
– Obligation (weaker): You should pay your bills.
– Expectation: The train should arrive soon.

6. Will / Would

Will:
– Future actions: I will call you.
– Promises or decisions: I’ll help you.
– Certainty: It will be fine.

Would:
– Polite requests: Would you like some tea?
– Imaginary situations: I would go if I had time.
– Past habits: He would always bring me coffee.

7. Ought to / Need / Dare / Used to

Ought to:
– Similar to should: You ought to be careful.

Need:
– Modal: Need you go now?
– Regular: You need to go.

Dare:
– Rare modal: Dare he speak?

Used to:
– Past habits: I used to play soccer.

8. Sentence Structure

Positive: Subject + modal + base verb
– She can drive.

Negative: Subject + modal + not + base verb
– He should not eat that.

Question: Modal + subject + base verb
– May I help you?

9. Common Mistakes

❌ She cans swim. ✅ She can swim.

❌ He musts go. ✅ He must go.

❌ Do you can help? ✅ Can you help?

❌ You mustn’t to smoke. ✅ You mustn’t smoke.

10. Practice Resources

1. British Council – Modals Practice

2. Cambridge – Modal Verbs Activity

3. Perfect English Grammar – Modals Guide

11. Quick Reference Table

ModalUseExample
canability, permissionI can help.
couldpast ability, politeCould I ask?
maypermission, possibilityMay I come in?
mightpossibilityHe might be late.
mustobligation, deductionYou must stop.
have toobligationI have to work.
shallsuggestionShall we dance?
shouldadvice, expectationYou should rest.
willfuture, decisionI will call you.
wouldpolite, hypotheticalI would go if I could.

12. Conclusion

Modal verbs are essential for expressing meaning clearly and politely in English. They help show ability, possibility, permission, and more. Though they seem simple, choosing the right modal is important for accuracy. With practice, you can use them correctly in everyday speech and writing.

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