Question

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

[　　]

A．invited

B．inviting

C．being invited

D．having invited

Answer 1

答案：A
解析：

主句主语与invite具有被动关系，故此处应使用表被动关系的过去分词invited。unless invited to speak相当于unless you are invited to speak。故正确答案为：A。 　　句意：除非你被邀请讲话，否则在会议上你应该保持沉默。