20.It is uncertain whether the medicine will work on the this cold, _________？

A. won't it　　　 　 B. isn't it　　 C, will it　　　 　　 D. is it

19.It is definite that new digital mobile phones have less radiation, but that does not__________mean

that they should be used without caution.

A. eventually　 　 B. necessarily　　　 C. generally　 　　 D. obviously

18.______________the advantages against the disadvantages, I decided to take up the job as a clerk in the bank.

A. Having weighed B. Weighing　 　 C. Weighed 　 D. To weigh

17.The previous lecture focused on the reading problems in new words, while this lecture will turn to

　　　 ___________in complex sentence structures.

A. ones　 B. one　 C. those 　 D. that

16.Being exposed for a long time_____strong sunlight might seriously damage your skin.

A. over　　 B. under　 　 C. to　 　　　 　D. in

15.It' s quite a time ______Yao Ming got injured, but it won' t be long________he returns to

the court.

A. that; when　 B. after; when　 C. before;since　 D. since;before