perfect verb forms

construction
Perfect verb forms are made with have + past participle.
She has lost her memory, (present perfect)
They have been living in France for the last year, (present perfect progressive) •
I told him that I had never heard of the place, (past perfect)
When I went back to the village the house had been pulled down.
(past perfect passive)
We will have finished by tomorrow afternoon, (future perfect tense)
I’m sorry to have disturbed you.
(perfect infinitive)
Having seen the film, I don’t want to read the book, (perfect -mg form)
terminology and use
A perfect verb form generally shows the time of an event as being earlier than some other time (past, present or future). But a perfect form does not only show the time of an event. It also shows how the speaker sees the event – perhaps as being connected to a later event, or as being completed by a certain time. Because of this, grammars often talk about ‘perfect aspect’ rather than ‘perfect tenses’.
For details of the use of the various perfect verb forms, see the individual entries in the book.