Infinitives may occur with or without the infinitive marker "to". Infinitives without "to" are known as "bare infinitives".
The infinitive can have the following forms:
- The perfect infinitive
to have + past participle
For example: to have broken, to have seen, to have saved.
This form is most commonly found in Type 3 conditional sentences, using the conditional perfect.
- 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
For example: 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
Examples: 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
For example: 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.
NOTE: As with the present infinitive, there are situations where the "to" is omitted.Examples
- He claimed to be an expert.
- I managed to reach the top of the hill.
- Don't pretend that you know the answer.
- She failed to explain the problem clearly.
- The customs man demanded to search our luggage.
- I can't afford to go out tonight.