It is required that no smoking in the school.A. was allowedB. be allowedC. would be allow

问题补充：

It is required that no smoking in the school.

A. was allowed

B. be allowed

C. would be allowed

D. had been allowed

答案：

A. was allowed

(答案→)B. be allowed

C. would be allowed

D. had been allowed

解析：考查虚拟语气中的(should) + v 的形式。