. You have a big mouth, Tom. You _______ have told everybody the secret.
21.The doctor couldn’t answer the question _____ the patient could survive that night.
20.---I got up at five this morning, I thought it was Friday. ---You _____ so early.It is Sunday today; you don’t have to go to work.
19.He says he really can’t _____ to wait another day.
18.---I can’t recite the poem. ---Well, you are supposed _____ it many times yesterday evening.
17.---May I surf the Internet tonight? --- No, you ______.You must do the exercises.