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

--- I think a bridge ________ over the river.

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

1. A.
   should be built
2. B.
   is being built
3. C.
   has been built
4. D.
   was built

--- 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