20.　 When we are in Beijing, they gave an ___________(招待)to us.

Unit 13

19.　 No country should neglect the e_________of its young people.

18.　 She is interested in __________(环境保护).

17.　 The ________(文明)of mankind has taken thousands of years.

16.　 All eyes were f________on the speaker.

15.　 He gave me an apple in ________(交换) for a cake.

14.　 There is a l______to everything; you should not always act like that.

13.　 The enemy tried to c______off our way back, but didn’t succeed.

12.　 Everyone who has been to the Tian’anmen Square can’t help ______(赞赏)it.

11.　 The time of waiting seems e________.