Unit 2 - People
Perfect Modal Verbs (Possibility)
Express past possibilities and speculations with modal + have + past participle.
1. From Present Guess to Past Possibility
B1 deduction: He must be tired after such a long day.
B2 upgrade: He must have been tired after such a long day.
Perfect modals = modal + have + V3 to talk about past situations.
2. Modals for Possibility
| Modal | Meaning | Example |
|---|---|---|
| may/might have | Past possibility, neutral | She might have forgotten the meeting. |
| could have | Past possibility (often unrealised) | We could have taken an earlier train. |
| can’t have | Strong negative deduction | They can’t have left already. |
| must have | Strong positive deduction | The team must have worked all night. |
3. Form Notes
- Modal + have (not of) + past participle.
- No change for subject; modals stay the same.
- Add not after the modal: might not have, couldn’t have.
Spoken contractions
You’ll often hear must’ve, might’ve, could’ve—be careful not to write must of.
4. Practice
- Write five sentences speculating about what happened yesterday.
- Change present-tense deductions into perfect modal sentences.
- Create negative deductions using can’t/couldn’t have.
Quick Review
- Perfect modals express how certain you are about past events.
- Use might/may/could have for possibilities, must have for strong conclusions, can’t/couldn’t have for impossibility.