Consequence of tenses

When I ______ (look) out of the window, I ______ (see) John.

______ you ever ______ (play) the piano since you left school?

I ______ (not see) him for two days.

When he ______ (try) to open the door, he ______ (drop) his key.

They ______ (live) in this house since 1987.

My father ______ (wash) his car while my mother and I ______ (prepare) dinner.

______ you ______ (meet) her yesterday?

Mary ______ (be) in London for three days.

The headmaster ______ (enter) the classroom when they ______ (write) their exams.

He ______ (buy) a new car last week.