Perfect Infinitive (Have + Past Participle)

Perfect infinitives (have + past participle) can be used after modal verbs could, might, ought, should, would and needn’t to refer to unreal situations.

  • could have married her if I wanted to. (I didn’t marry her.)
  • That was dangerous – he could have killed somebody. (He didn’t kill anybody.)
  • You should have written – I was getting worried. (The person did not write.)
  • She needn’t have invited them. (She invited them.)
  • You were stupid to try climbing up there. You might have killed yourself. (The person didn’t kill himself.)
  • If she hadn’t been so bad-tempered, I might have married her. (I didn’t marry her.)
  • ought to have phoned him this morning, but I forgot.

Grammar notes

The structure modal verb + perfect infinitive does not always refer to an unreal situation. It can also be used to talk about possibility.

  • She could/should/ought to/may/might/will have arrived by now.

Manjusha Nambiar

Hi, I am Manjusha. This is my blog where I give English grammar lessons and worksheets.

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