20.　　 On Friendship Day no ______(争论) or fights are allowed. 　

　Keys:

19.　　 It is bad manners to _______(打断) others’ talk.

18.　　 That certainly seems a satisfactory _______(解释).　　　

17.　　 It is said that some ants have double _______(胃).

16.　　 Some people tend to cry in _______(激动).

15.　　 The children were lying flat on their　　　　　 (肚子) 　

14.　　 ( 逐渐)，the children began to understand. 　

13.　　 Leaving ground floor windows open will encourage　　　　　 (贼) 　

12.　　 He finally 　　　　　　(实现)his aim through hard work..

11.　　 Wear your boots, or you may get　　　　　 (咬)by snakes.