They are uncertain_________ the time they________.

　　　　A. about; arrive　　　　　　　　　　B. about; will arrive

　　　　C. for; arrive　　　　　　　　　　　D. for; will arrive

The teacher told us that light ______ faster than sound.

　 A. traveled　　　 B. had traveled　　　 C. is traveling　　　 D. travels

Only when your identity has been checked ____________.

A. you are allowed in　　　　　　　 B. you ’ll be allowed in

C. will you allow in　　　　　　　　 D. will you be allowed in

The room ________ windows face north is a mess.

　 A. that　　　　　　　 B. where　　　　　　 　 C. whose　　　 　 D. which

_______ my opinion, you shouldn’t go there by yourself.

A. On 　 B. To　 C. In 　 D. At

I ________________________(正专注于)a book and didn’t hear you call.

Many countries, for example, Mexico and Japan, _____a lot of earthquakes.?

A. have　 B. having　 C. to have　 D. having had

The reason for all the changes being made__________to us yet.?

A.has not explained?

B.has not been explained ?

C.did not explained?

D.were not explained ?

Tom is ______ because he never takes any exercise.
A. under conditions   B. on no condition   C. in condition   D. out of condition

The men will have to wait all day ______ the doctor works faster.

　 A. if　　　　　　 B. unless　　 C. whether　　　 D. that