问题补充:
They demanded that the library open to students during the vacation.
A. should keep
B. was kept
C. would be kept
D. be kept
答案:
A. should keep
B. was kept
C. would be kept
(答案→)D. be kept
解析:考查虚拟语气:主句的动词是demand,从句的谓语用(should) do表示虚拟语气,the library和keep是被动关系,用be kept,句意:他们要求假期图书馆向学生开放,选D。