20.---------How often do you go to the library?

---------_______.

A. Every a few days　　　　　　　　 B. In no time　　　　　

C. From time to time　　　　　　　　 D. In two days

19. Jane didn’t follow our advice that she _____ more attention to her pronunciation.

A. be paid　　　　　 B. must pay　　 C. pay　　　　　　 D.would pay

18. Nobody but doctors or nurses and those ___ by Dr Zhang ___ to enter the patient’s room.

A. invited, is allowed　　　　　　　 B. are invited, are allowed　

C. is invited ，is allowed　　　　　 D. invited, are allowed

17.We hope to go to the beach tomorrow, but we won’t go __________ it’s raining.

　A .if　　　　　　　　　　 　 B.when　　　 　 C.though　　　　　 　　　 D.because

16._____ from the moon, our earth looks like a “ blue ball.”

A.Seeing　　　　　 B.To see　　　 C.See　　　　　　 D.Seen