The students are forbidden，unless they have special passes， after 11 p.m.
A. of staying out
B. to stay out
C. staying out
D. stay out
网友回答
A. of staying out
(答案→)B. to stay out
C. staying out
D. stay out
解析：考查动词forbid的搭配形式。此句正常语序应该把unless的从句放后面，所以考查的forbid sb. to do sth“禁止某人干某事”，学生被禁止呆到晚上11点之后，用被动形式表达。所以答案选择B。