题目内容：

The dean tried to retain control of the situation on campus,but his attempt was ___ by the board of trustee.
A.approved B.frustrated C.disclosed D.justified.

优质解答

院长试图控制校园里的形势,但他的尝试被董事会阻挠了.
因为有but,所以前后是转折关系,A赞成,意思不对,B阻挠（√）C公开揭露D证明、辩护.
所以B