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

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：句意：--对于山村的这些孩子穿过这条河上学是困难的，---我认为一座桥应当在在河的上面，should be done应当被允许做某事根据题意故选A。