Grammar · Sentence structure
Modal verbs
Formula: can, could, will, would, shall, should, may, might, must
B1
Quick answer
The 5 main uses
1. Can / could
Ability or permission. Can = present; could = past, or a more polite request.
“I can swim. Could you help me?”
2. Will / would
Will = future; would = conditional.
“I'll come tomorrow. I would love to.”
3. Shall / should
Shall = a suggestion; should = advice.
“Shall we go? You should rest.”
4. May / might
Possibility. May = more likely; might = less likely.
“It may rain. It might rain.”
5. Must
A strong obligation, or something you are sure is true.
“You must wear a uniform. He must be tired.”
Common mistakes to avoid
No to after a modal
All modals are followed by the base form without to: I can swim, You must go, never I can to swim.
No -s with he, she, it
Modals never change: She can, He must, never She cans. This is a big difference from ordinary verbs.
No do in questions and negatives
Modals are auxiliaries themselves. Question: Can you...? Negative: I can't. No do: Do you can swim? ✗.
Related pages: Modal verbs
Pages on a similar topic or with a similar use, so you can keep exploring.
Going further
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Frequently asked questions
What are the modal verbs in English?+
The 9 modals: can, could, will, would, shall, should, may, might, must. They express ability, permission, the future, the conditional, possibility and obligation.
Why don't modal verbs take -s with he, she, it?+
Modal verbs never change their form. It is a special rule: she can (not she cans), he must (not he musts). It is a very common mistake for beginners.
Why is there no to after a modal verb?+
Modal verbs are followed by the base form (the infinitive without to). I can swim ✓ / I can to swim ✗. This is a strict rule. Exception: ought to (less common) keeps its to.
How do you make questions and negatives with modal verbs?+
The modal is itself the auxiliary. Question: modal + subject (Can you...? Should I...?). Negative: modal + not (I cannot / I can't). You don't need do/does/did.
What is the past of modal verbs?+
Some modals have a past form, used for example in reported speech: can → could, will → would, shall → should, may → might. Must has no past form: use had to. To talk about something that was possible in the past, a regret or a criticism, use modal + have + past participle: could have, should have (I should have studied).
Updated on 6 November 2026 by the Big Challenge teaching team. Every year, more than 500,000 students across Europe take part in our English contest, created in 1999. Our teaching approach →
The Big Challenge · Updated on 6 November 2026 · Source: www.thebigchallenge.com/bl/academy/learn-english/grammar/modal-verbs
© The Big Challenge. Copying allowed for classroom use. Every year, more than 500,000 students across Europe take part in our English contest, created in 1999.