18.   The National Labor Relations Act expressly forbids unions from engaging in secondary boycotts against companies not directly involved in a labor dispute.

(A) unions from engaging in

(B) the engagement by unions of

(C) unions to engage in

(D) unions from becoming engaged with（C）

(E) that unions engage upon

答案c

a为什么不对

明明有forbid from doing 这种用法的嘛

谢谢

在《Oxford Advanced Learner's English-Chinese Dictionary》里分明有forbid sb from doing sth（禁止，不准）的用法啊！

例句是：He forbade them from mentioning the subject again.