The infinitive can have the following forms:

NOTE: as with the present infinitive, there are situations where the to is omitted, e.g. after most modal auxiliaries.

The perfect infinitive:

to have + past participle, e.g. to have broken, to have seen, to have saved.

This form is most commonly found in Type 3 conditional sentences, using the conditional perfect, e.g. If I had known you were coming I would have baked a cake.


  • Someone must have broken the window and climbed in.
  • I would like to have seen the Taj Mahal when I was in India.
  • He pretended to have seen the film.
  • If I’d seen the ball I would have caught it.
The continuous infinitive:

to be + present participle, e.g.to be swimming, to be joking, to be waiting


  • I’d really like to be swimming in a nice cool pool right now.
  • You must be joking!
  • I happened to be waiting for the bus when the accident happened.
The perfect continuous infinitive:

to have been + present participle


  • to have been crying
  • to have been waiting
  • to have been painting 

  • The woman seemed to have been crying.
  • You must have been waiting for hours!
  • He pretended to have been painting all day.
The passive infinitive:

to be + past participle, e.g. to be given, to be shut, to be opened


  • I am expecting to be given a pay-rise next month.
  • These doors should be shut.
  • This window ought to be opened.