Choose the best answer to complete each sentence 

There is one _______ thing we can be sure: _______ energy will be morechallenging and more important in the future.

A. improving   

B. making                   

C. saving                                

D. employing

A. into             

B. up to                       

C. out of                                 

D. away from

A. up to now, we have designed some solar cars.

B. solar cars have been very popular for many years.

C. we have not produced any solar cars yet.

D. solar cars are not as much appreciated as other kinds of car.

A. powerful    

B. medical      

C. dangerous   

D. computer

A. assist

B. increase      

C. make         

D. create

A. Cancers and AIDS, which are untreatable now, will be cured successfully.

B. Cancers and AIDS, they are untreatable now, will be cured successfully.

C. Cancers and AIDS, that are untreatable now, will be cured successfully.

D. Cancers and AIDS, which are untreatable now, they will be cured successfully.

A. communication                  

B. education                

C. medicine                             

D. technology