/Modal Verbs
A2Modal Verbs

Modal Verbs Overview

1

What is it?

Modal verbs are special auxiliary (helping) verbs that express ability, possibility, permission, obligation, and more. They are always followed by the base infinitive and never change form. Common modals include: can, could, will, would, shall, should, may, might, must, and ought to.

2

How to form it

SubjectPositiveNegativeQuestion
I/You/He/She/It/We/TheyShe can swim. / You must leave.He can't drive. / You mustn't go.Can she swim? / Must we leave?
  • • Modals never change form — no -s for third person: "He can" (NOT "He cans").
  • • Always followed by base infinitive (no "to"): "You must go" (NOT "You must to go").
  • • Negatives: add "not" directly after the modal: "cannot / can't", "should not / shouldn't".
  • • Questions: invert the modal and subject: "Can you help?" / "Should I stay?"
  • • "Ought to" is the exception — it uses "to": "You ought to apologise."
3

When to use it

  1. 1

    Ability: can / could / be able to

    She can speak three languages.

  2. 2

    Possibility: may / might / could

    It might rain later.

  3. 3

    Permission: can / may / could

    Can I borrow your pen?

  4. 4

    Obligation / necessity: must / have to / should

    You must wear a seatbelt.

  5. 5

    Advice / recommendation: should / ought to

    You should see a doctor.

  6. 6

    Requests and offers: will / would / could

    Could you help me, please?

4

Common mistakes

She cans swim very well.

She can swim very well.

Modal verbs never add -s for the third person.

You must to leave now.

You must leave now.

Modal verbs are followed by the bare infinitive — no "to".

He should goes to the doctor.

He should go to the doctor.

After modal verbs, always use the base form of the main verb.

5

Quick reference

  • Modals: can, could, will, would, shall, should, may, might, must, ought to.
  • No -s in third person: "She can" not "She cans".
  • Always followed by bare infinitive (no "to").
  • Negatives: modal + not (can't, shouldn't, mustn't).
  • Questions: modal before subject (Can you? Should I?).
  • Each modal has multiple meanings depending on context.
6

Natural conversation example

A student is asking her teacher about modal verbs.

S

Student

Can you explain modal verbs? I always get confused.
T

Teacher

Of course! Modal verbs are words like can, should, must, and might.
S

Student

And they never change? Like, we don't say "She cans"?
T

Teacher

Exactly. No -s for third person. And no "to" after them — just the base verb.
S

Student

So "You must to go" is wrong?
T

Teacher

Right — it should be "You must go". "Ought to" is the only exception.
S

Student

I think I might understand now.
T

Teacher

You definitely do! And notice — you just used a modal correctly!

Practice Exercises

Fill in the blank with the correct modal verb from the box: can, should, must, might, would, could.

  1. 1.
    You __ wear a seatbelt by law. (obligation)
  2. 2.
    She __ speak four languages. (ability)
  3. 3.
    It __ rain later — bring an umbrella just in case. (possibility)
  4. 4.
    You __ see a doctor about that cough. (advice)
  5. 5.
    __ I help you with that? (offer)
  6. 6.
    __ you pass the salt, please? (polite request)
  7. 7.
    He __ swim when he was five. (past ability)
  8. 8.
    You __ smoke here — it's forbidden. (prohibition)
  9. 9.
    They __ arrive any minute now. (possibility)
  10. 10.
    I __ love a cup of tea right now. (desire)
All TopicsModal Verbs of Ability

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