must have done (modal + perfect)
must have done (modal + perfect) means “Modal + have + past participle: guessing or concluding about the past”. Modal + have + past participle draws a conclusion about the past from present evidence: You must have made a mistake. Formation: modal + have + past participle
Modal + have + past participle: guessing or concluding about the past
B2Formation
modal + have + past participle
Explanation
Modal + have + past participle draws a conclusion about the past from present evidence: You must have made a mistake. The modal shows certainty — must (I'm sure it happened), might, may or could (perhaps it did), can't or couldn't (surely it didn't) — and have + participle points back to a finished past event. It is active here: the subject did the action. Compare It must have been done, which is the passive.
Examples
Note
For deduction, can't have (not mustn't have) is the negative of must have: She can't have left already. Mustn't means obligation, not disbelief.
FAQ
must have done (modal + perfect) — what does it mean and how is it used?
Modal + have + past participle: guessing or concluding about the past. Modal + have + past participle draws a conclusion about the past from present evidence: You must have made a mistake. The modal shows certainty — must (I'm sure it happened), might, may or could (perhaps it did), can't or couldn't (surely it didn't) — and have + participle points back to a finished past event. It is active here: the subject did the action. Compare It must have been done, which is the passive.
must have done (modal + perfect) — how do you form it?
modal + have + past participle
must have done (modal + perfect) — any usage notes?
For deduction, can't have (not mustn't have) is the negative of must have: She can't have left already. Mustn't means obligation, not disbelief.