2 . Black holes________not be seen directly so determining the number of them is a tough task.

A．can

B．should

C．must

D．need

3 . 在我看来，学生应该多听多说，以便能培养他们的沟通技巧。
As far as I am concerned，students should do more listening and speaking________________.

7 . 选词填空。
1. Robert is good at languages and ________(can/must) speak four languages.
2. The meeting is very important and you________(would/should) attend it on schedule.
3. I managed to find the street, but I ________(couldn’t/mustn’t) find her house.
4. Every Sunday afternoon, the boy ________(will/may) sit there hour after hour looking at the traffic go by.
5. In his childhood, Jack ________(would/could) be nervous when he met strangers.
6. —Do you have any plan for this weekend?
—I have not decided yet. I________(may/need) take my daughter to the museum.
7. According to the doctor’s advice, the medicine________(might/must) be taken three times a day.
8. No one ________(shall/must) stop us from carrying out the plan.
9. Rose ________(can’t/needn’t) be in the classroom now, because I saw her leave school several minutes ago.
10. Jane asked whether she________(must/could) sit in the empty seat.
11. One of the windows of the classroom ________(won’t/mustn’t) close, so I’ll have it repaired.
12. The headteacher warned him not to be late for school, but Jack ________(wouldn’t/shouldn’t) listen.

10 . 游客也可花上数小时，一探此地的中国味道与美景声色。（spend...doing sth）(汉译英)