--- 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
网友回答
(答案→)A. should be built
B. is being built
C. has been built
D. was built
解析：考查被动语态。“乡村的孩子很难通过这条河去上学。”“我认为应该在河上建一座桥。”bridge和build之间是被动关系，应该用被动语态；且句意表示的是将来的情况。故用一般将来时。故选A。