1 . — Why don’t you enter the office? They are waiting for you.
— The door ________ open, no matter how hard I pushed.

A．won’t

B．can’t

C．mustn’t

D．needn’t

2 . If fish are jumping higher than usual or frogs are croaking more loudly, it________ rain.

A．must

B．may

C．shall

D．need

3 . The designer has tried every possible way to make the robot light, so you_______worry about its weight.

A．must

B．may

C．can't

D．needn't

4 . In order to make our dreams come true, we _______ work hard.

A．must

B．can

C．need

D．may

5 . —Mom,_____I hang out with Susan now?
—No,you_____.It’s dangerous for two girls to be outside at night.

A．could;can’t

B．could;needn’t

C．should;can’t

D．must;couldn’t

6 . Both drivers and passengers         wear seat belts while their cars are running on the highway.

A．must

B．can

C．may

D．need

7 . —_________I go with my friends to the harvest festival?
—No. you’d better not.

A．Must

B．May

C．Would

D．Need

8 . 尽管条件极其艰苦，我们必须坚持下去，直到成功。
We must ________ ________ till success in spite of the extremely difficult conditions.

9 . 选用适当的单词或短语补全对话
Boss: All the documents     1     （must/can） be prepared before the meeting starts
Secretary: I know that. Kelly has been working on the documents since last Monday. She     2    （may/must）have got everything ready but I am not sure.
Boss: Wheres Kelly then?
Secretary: She     3     （must/has to）be in the sales managers office now. I saw her go in there a minute ago.