填空:Unless[ ](invite)to speak,you should remain silent at the conference.

问题描述:

填空:Unless[ ](invite)to speak,you should remain silent at the conference.

这是一个省略句,从句应该是被动的,意思是:
除非你被邀请说话,否则在开会时就应该保持沉默.
填invited
相当于:
Unless you are invited to speak,you should remain silent at the conference.