9.　　 Can you give me a s__________ knife so that I can cut off the s________细绳)？

8.　　 Do you have an __________(电) fan to cool in summer?

7.　　 Don’t worry about anything! Everything is under c__________!

6.　　 Einstein’s theory __________(证明) to be true at last.

5.　　 People now use paper instead of a h__________ to clean their faces.

4.　　 Which do you prefer to use to wash your hair, soap or s__________?

3.　　 Do you know why l________ comes into sight before t_____ comes into our ears?

2.　　 If you are feeling cold, you needn’t take off your g______ to protect your hands.

1.　　 Students must c_________(做) e_______ when they study physics or chemistry.

20.　 He went into his room on the second floor through the window with a l______ because he had left his keys in his room.

Unit 16