The passive infinitive is used in some constructions using the passive voice. It is particularly common after auxiliary verbs (may, should, could, etc.) to indicate what is possible or what is correct. The passive infinitive is formed:
to be + past participle
As with the present infinitive, there are situations where the zero form of the passive infinitive is required, so the word to is omitted. This happens after most modal auxiliaries, and in other places where zero infinitives are used.
- I am expecting to be given a pay-rise next month.
- She is hoping to be elected president.
- The carpet needs to be washed.
- These doors should be shut at night.
- This window may be opened but that one must stay closed.
- Alice could be given a prize for her artwork.