It’s difficult for the village children to cross the river for school.I think a br

问题补充：

--- It’s difficult for the village children to cross the river for school.

--- I think a bridge over the river.

A. should be built

B. is being built

C. has been built

D. was built

答案：

(答案→)A. should be built

B. is being built

C. has been built

D. was built

解析：由题意判断是桥还没建起来。B C D 的意思是 建起来了 A 应该被建，但还没建