155. The teacher was a little angry because the students didn’t _____ their exercise books on time.
You needn’t have ________ the speaker when he was speaking; there was enough time afterwards for you to ask questions.
It’s helpful to put students in a situation _______ they can learn how to cooperate with each other.
How I wish I _________ him the secret! I regret having done that now.
—Who do you think will get the first prize? —Mary, of course. She ________ for the competition for months.
—Who do you think will get the first prize?
—Mary, of course. She ________ for the competition for months.
All his time _______research on Chinese history, he has no time for outdoor activities.