Unless to speak, you should remain silent at the conference. A invited B invitin

Unless ____ to speak,  you should remain silent at the conference.

A invited         B inviting           C being invited    D having invited

试题答案

A

解析:

本题考查动词的-ed形式。You 与invite 之间构成被动关系，故用过去分词。Unless invited to speak = Unless you are invited to speak. 答案为A。