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 |