1.20世纪70年代，美国人发明了照相机和手机。

         ，Americans developed digital cameras and cellphones.

(   ) 5. —Do you think fresh water can       on earth one day?

      —I'm afraid so,if people don't save it. 

A. take out    B. go out 

C. run out    D. put out

(   ) 4. —Do you take exercise every day?

      —Yes. It usually      me about half an hour to do that.

A. spends    B. costs

C.takes    D. pays

(   ) 3.——What do you think of your new classmate?

     ―She              has good grades       is glad to help others.

A.   too... to

B.   not only... but also

C.   both... and

D.   so... that

(   ) 2. We think human beings may live on the moon in the future.       no

one is sure about it.

A. While    B. Whatever

C. Since    D. However

(   ) 1. We all know that learning a language      time and effort.

A. requires    B. reduces C. removes    D. reuses

5 .You need a      (向导)to show you around the city.

4. There are plenty of resources in the         (深的)ocean.

3. ―How long will you              (需要)to finish the work? —About three days.

2. Kris and Karl come from Europe. They're____ (德国人）.