问题
选择题
---It’s difficult for the villagers to cross the river.
---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
本题考查的是情态动词的被动语态，其结构为主语+情态动词+be+动词过去分词，故选答案为A