With temperature ______ so rapidly, we could not go with the experiment．
| A．fall | B．falling | C．fallen | D．to fall |
He ought to win the first prize, _____ he?
| A．oughtn’t | B．shouldn’t | C．mustn’t | D．both A and B |
I missed the last bus, so I _____ go home on foot.
| A．must | B．have to | C．may | D．had to |
I got up early that morning, but I _____ so because I had no work to do.
| A．mustn’t have done | B．didn’t need to do | C．needn’t have done | D．can’t have done |
You must be a writer, _____?
| A．mustn’t you | B．are you | C．must you | D．aren’t you |
She’s already two hours late. What ______ to her?
| A．can have happened | B．may have happened |
| C．should have happened | D．must happen |