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.

1. explained　 2. besides 3.author　 4. prettier　 5. rehearsing; perform　e 7.diamond; necklace　 8. recognized　 9. mystery 10. continued　 11. palace　 12. exactly　 13. outline　 14. mosquitoes 15. debts　 16. positive　 17. quality 18.lecture　 19. earn　 20. ladder

Unit 16

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.

19.　 He worked day and night, trying to e_______ much more money.

18.　 --Where are you going?

--Oh, there goes the bell. I am going to listen to the l_______ given by Dr. Li.