Perfect Modals – Must Have
PERFECT MODALS are based on the PRESENT PERFECT grammar form which is:
Subject + (v)have + past participle
The form of a Perfect Modal is:
Subject + modal + have + past participle
The nine modals are:
can, could, will, would, may, might, must, shall & should
PERFECT MODALS are used to refer to something in the past.
The meaning changes depending on which MODAL you use.
is used to make a logical conclusion about something in the past
For example, imagine you and your friend were talking in the school cafeteria ten minutes ago.
You excused yourself to go and use the washroom.
You return to the cafeteria. Your friend is not there. His jacket is gone and his dishes have been cleaned up.
You think, “He must have left.”
This is a logical conclusion. The facts that you have (logic) lead you to this answer (conclusion). You do not know for sure, but based on the information you have, this is a probable answer.