The rule demands that everyone quiet in the school library.
A. keeps
B. keep
C. will keep
D. should be kept
网友回答
A. keeps
(答案→)B. keep
C. will keep
D. should be kept
解析：考查虚拟语气：句意：规定要求每个人在学校图书馆保持安静。主句的动词是demand“要求”，宾语从句的谓语用虚拟语气，sb （should） do，这里用keep省略should。选B。