—Listen! There is a knock on the door.Who _____ it be?—It must be Jack.Just now I sent for him.
I _____ as soon as you come back.
The scientist _____ Canada and he will give us a talk when he _____ back.
He found his book this morning, but now he _____ his pen.
She ____ to her hometown several times.
It _____ Jane and Mary who helped me the other day.