No one is allowed in the classroom.A. smokingB. smokeC. smokedD. to smoke

问题补充：

No one is allowed in the classroom.

A. smoking

B. smoke

C. smoked

D. to smoke

答案：

A. smoking

B. smoke

C. smoked

(答案→)D. to smoke

解析：本题的含义是没人被允许在课堂上抽烟，允许某人做某事可用allow sb to do sth，故本题选D。