Passengers are to look out of the window when the train is moving.
A. forbidden
B. kept
C. prevented
D. banned
网友回答
(答案→)A. forbidden
B. kept
C. prevented
D. banned
解析：forbid sb to do sth意思为 “禁止某人做某事”, 被动结构为 be forbidden to do sth。而 be kept from doing sth；be prevented from doing sth；be banned from doing sth。