It was quite a serious accident, _____ caused by careless driving.
| A．which I think was | B．I think which was |
| C．which I think it was | D．I think which it was |
----I called you yesterday. A woman answered, but I didn’t recognize her voice.
----Oh, it _____ my aunt Jean.
| A．must be | B．must have been |
| C．might be | D．can have been |
---I called you yesterday. A woman answered, but I didn’t recognize her voice.
----Oh, it _____ my aunt Jean.
| A．must be | B．must have been |
| C．might be | D．can have been |
It’s a very kind offer, but I really _____ accept it.
| A．mustn’t | B．needn’t | C．can’t | D．don’t |
This cake is very sweet. You _________ a lot of sugar in it.
| A．should put | B．could have put | C．might put | D．must have put |
—Catherine, I have cleaned the room for you.
—Thanks. You _________it. I could manage it myself.
| A．needn’t do | B．needn’t have done |
| C．mustn’t do | D．shouldn’t have done |