Intermediate 📐 Grammar · #120 of 305

Modal Verbs of Deduction (Past)

must have, can't have, might have + pp.

Examples

  • She must have left.

Key rules

  • Form: modal + have + past participle
  • Must have = sure it happened
  • Can't/couldn't have = sure it did not
  • May/might/could have = possible
  • Use have, not had

Common mistakes

  • He must had forgotten → He must have forgotten
  • She can't has left → She can't have left
💡 Tip: Use these for guesses about past events with evidence.
Practise this topic in the appPractise Intermediate quiz
← Modal Verbs of Deduction (Present)Needn't Have and Didn't Need To →

Related Intermediate topics

See all Intermediate grammar lessons →

Present Perfect Continuous

have been + -ing stresses duration up to now.

Past Perfect

had + past participle for an earlier past action.

Past Perfect Continuous

had been + -ing for duration before a past moment.

Future Continuous

will be + -ing for actions in progress at a future time.

Future Perfect

will have + past participle for completion before a future time.

Future Perfect Continuous

will have been + -ing for duration up to a future point.