____ for a long time, most of the crops in this area died from lacking water.

A. /; the

B. /; /

C. the; /

D. the; the

A. will he be

B. does he come

C. he will be

D. did he come

A. who is

B. who am

C. that is

D. what is

A. sum

B. summed

C. will sum

D. would sum

A. by whom

B. for whom

C. through which

D. in which

A. What；what

B. What；that

C. That；that

D. That；what

A. if

B. weather

C. if or not

D. whether

A. when

B. where

C. which

D. that

A. that

B. where

C. which

D. when

A. when

B. why

C. what

D. that