1 . She ________ (participate) in the activity, for she was doing paperwork in the office then. （用适当的词填空）

2 . 据说他们是从大陆游到那个岛的，但他们不可能做到，因为中间的海洋太宽了。
It’s said that they have swum to the island from the continent, but they ________________ it because the ocean in between is too wide.

3 . You ________ have seen Mary at the meeting this morning, because she left for Beijing yesterday. (用适当的词填空)

4 . I dare ________ that without your help, we ________ so much progress in our work.

A．say; can’t make	B．to say; couldn’t make
C．say; couldn’t have made	D．to say; shouldn’t have made

5 . Mr. Smith ________________, for I saw him in the library just now.
史密斯先生不可能去了北京，因为我刚才在图书馆看到他了。

6 . But for his timely help, we ______ our task in such a short time.

A．wouldn’t finish	B．haven’t finished
C．couldn’t have finished	D．can’t have finished

7 . 选词填空
1. —Must I finish the task right now?
—No，you ________ (don’t have to/mustn’t)
2. It’s so near. We ________ have taken a taxi.(shouldn’t/can’t)
3. You ________ have spent so much time playing computer games.(mustn’t/oughtn’t to)
4. ―Shall I leave the room so that you two can talk?
―No, you ________.(mustn’t/needn’t)
5. He ________ have missed the train; he arrived atthe train station two hours earlier.(can’t/mustn’t)
6. You ________ start at once if you want to catch the bus.(have to/ought to)
7. They ________ stay in the office last night because of the snowstorm.(had to/must)
8. We _______ have helped him; in that case, he would have been able to finish the work.(should/can)
9. He finished all the work himself; in fact, he ________ have asked his friends for help.(need/could)
10. Something terrible ________ have happened if Li Chang was not coming to eat in his restaurant as he always did.(have to/must)

9 . I __________you when I was in Paris as I didn’t know your address.

A．should have visited	B．couldn’t have visited
C．must have visited	D．can have visited

10 . 史密斯先生昨天不可能去北京了，因为我刚才在图书馆看见他了。(汉译英)