—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

提出"四时欲得小儿安，常要一分饥与寒"的专著是（）

A.《诸病源候论》

B.《小儿病源方论》

C.《备急千金要方》

D.《活幼口议》

E.《育婴家秘》