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Search concise B2 First grammar, vocabulary, functional phrases and exam strategy — without leaving the course to hunt through past lessons.
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What it is
Modal verbs used to say how certain you are about a situation, rather than to talk about ability or permission.
Form
| Type | Pattern | Model sentence |
|---|---|---|
| Certain (yes) | must + V · must have + V3 | She must know him. / She must have known him. |
| Certain (no) | can't + V · can't have + V3 | He can't be serious. / He can't have finished already. |
| Possible | might/may/could + V · + have + V3 | They might be waiting. / They might have left. |
| Question | Could/Might + subject + V? | Could she be at home? |
| Continuous | modal + be + V-ing · modal + have been + V-ing | He must be joking. / She may have been sleeping. |
Use it when
- You draw a conclusion from evidence.
- You speculate about a photo, situation or person in speaking tasks.
- You soften a strong claim you can't fully prove.
Examples
- The lights are off — they must be out.
- It can't be far; we've been walking for an hour.
- She might have missed the announcement.
- They could be discussing the results right now.
Watch out
He mustn't be at work — his car is here.
He can't be at work — his car is here.
Negative deduction uses can't, not mustn't (= prohibition).
She must has forgotten.
She must have forgotten.
Modals are followed by have, never has.
Remember
must = 95% yes · can't = 95% no · might/may/could = maybe.
Quick check
- 1.The grass is wet. It ___ (rain) last night.
- 2.That ___ (not / be) Tom — he's in Peru.