“When did he leave the classroom?” “He left _______ you turned back to write on the blackboard.”
| A．the time | B．the moment |
| C．until | D．since |
He asked me for this book many times. Please tell him that he _____ have it tomorrow.
| A．must | B．may | C．shall | D．both B and C |
Let us play basketball, ______?
| A．will you | B．don’t we | C．shall we | D．do you |
Let’s clean our classroom, _____?
| A．will you | B．don’t we | C．shall we | D．do you |
Everyone _____ do his best for the modernizations of our country.
| A．can | B．may | C．should | D．might |
31. He _____ have come here yesterday, but he didn’t.
| A．could | B．should | C．ought to | D．all the above |