20. It is 　　　　Du Li and Pang Wei married 　　　　they knew they are the first Olympic champion couple in our country .

　　　　 A. until, that　　 B. not until, which　 C.　 until , when　　　 D. not until, that

19.――It is really a heavy snow in early winter.　

　 ――　　　 .

A. So is it　　 B. No, it isn’t　　 C. I couldn’t agree more　　 D. As is it .

18.――Jenny looks very happy. She 　　　have won the first prize in the spoken English competition .

――I guess so. She speaks English fluently as if she were an American.

A. should　　　 B. could　　　 C. might　　　 D. must