Everyone be polite to the old people.A. mayB. shouldC. canD. could

问题补充：

Everyone be polite to the old people.

A. may

B. should

C. can

D. could

答案：

A. may

(答案→)B. should

C. can

D. could

解析：此题重点考查情态动词的用法，may可以，should应该，can能够，could是can的过去式，句意：每个人都应该对老年人有礼貌。根据句意可知选B。