| Form | subject + must / should / could + have + past participle; have never changes | She should have called. |
| Deduction: sure | must have: it happened; can't have: it did not | She must have left. / He can't have known. |
| Deduction: possible | may have, might have or could have: perhaps it happened | They might have missed the bus. |
| Regret and criticism | should have: not done; shouldn't have: done and wrong | I should have asked. / I shouldn't have shouted. |
| Unused chance | could have or might have: a chance that nobody took | You could have told me. |
| Unneeded action | needn't have: it was done and was not necessary | I needn't have hurried. |
| Unreal past | would have for the result of an unreal past condition | If I had known, I would have called. |
| C1Passive and continuous | after any modal: have been + past participle / V-ing | It must have been lost. / She can't have been sleeping. |
| C1Adverb inside | may well have: quite likely; can't possibly have: impossible | She may well have forgotten. / You can't possibly have finished. |
| C1Expectation and estimate | should have: expected by now; would have: an estimate | It should have arrived by now. / That would have been ten years ago. |
| C1Plan that failed | was to have + past participle: planned, but it did not happen | The bridge was to have opened in May. |
| Trap | write have or 've, never of | You should've called. |