20.What do you mean (　　　 )saying that?

18.If you are free ,please come over (　　 ) my house to have a rest.

17. Don’t laugh (　　　 )others when you are (　　　 ) trouble.

16.(　　　 )weekdays, I learn many lessons,(　　　　 )English,math and Chinese.

15. We are weak (　　　 ) math and Chinese.

14.He was ill (　　 )bed. I was worried (　　 　)him very much.

13.The answer depends (　　　 )what you think is right.

12. Can you give me some advice (　　　 )how to learn English?

11.Hundreds ( 　　) students are gathering on the square.

10.He is leaving (　　　 ) Shanghai tomorrow.