1. 根据句子或对话意思，从方框中选出适当的词或词组填空，注意其形式，每词限用一次。

can, may, must, mustn't, needn't, should, have to, had better

1. （1） Bill be ill at home. I'm not sure.
3. （2） — I return your bike tomorrow?

   —No, you .

5. （3） Rose sing English songs very well when she was five years old.
7. （4） —I have a fever.

   —You see a doctor at once.

9. （5） There was no bus. I walk home last night.
11. （6） —May I smoke here?

    —No, you . Look at the sign "No smoking" here.
    

13. （7） It's too cold outside. You do some activities indoors.