It is believed to have been built some time in the early twelfth century.
Sometimes we use a _____ to refer to something that might have happened in the past → He claims to have been the best student in his class when he was at school
Sometimes we use a _____ to refer to something we think will be completed at a certain point in the future → We expect to have finished the building work before the end of the year.
The _____ is formed by to have + been + verb+ing. It is used in the same way as the perfect infinitive, but the continuous form is used for actions and situations that happened, or might have happened, over a period of time.
The machine was supposed to have been repaired.
We form the _____ with to have + the -ed form of a verb. We use _____ after verbs such as claim, expect, hate, hope, like, love, prefer, pretend.
The _____ is formed to have + been + past participle.
We can use _____ in a clause with a verb that has no subject (a non-finite clause). It can refer to events which happened in the past → To have finished a marathon was, in itself, a great achievement
It can be used to refer to events that might have happened (but did not happen) → To have completed a marathon would have been a great achievement but he was satisfied with getting round just half the course
They seemed to have been arguing as their faces were red with rage
He claims to have been doing the gardening all day.