— We did not see him at the lecture yesterday．
— You ______ him, since I went to an international conference with him．
| A．mustn’t have seen | B．can’t have seen |
| C．couldn’t see | D．needn’t have seen |
___ is the most useful invention?
| A．Do you think which of these | B．Which of these you know |
| C．Which of these do you know | D．You know which of these |
We know such people are not ___.
| A．to rely on | B．to be relied upon | C．to be relied | D．to rely upon |
The article gave a ____ description of South America.
| A．live | B．alive | C．lively | D．living |
In my opinion, life in the twenty-first century is much easier than ____.
| A．what used to be | B．that it used to be |
| C．it used to be | D．what it used to be |
____ and we’ll get everything ready for the taking off.
| A．Have one more hour | B．If I have one hour more |
| C．Given one more hour | D．One more hour |