Поставьте глаголы в Past Indefinate,Past Continuous или Past Perfect
when does coach (to return) the students (to do) the forth exercise
the students (to do) all the exercises before the coach( to return)
we(to discuss )two important questions at last meeting
the runner already (to set)a new record before his friend came to the contest
we(to discuss )all the problems by 5 o"clock in the evening
when you phoned the students (to do)morning exercises