Question

【题目】You are not supposed to enter the teachers’ office ________ you are allowed to.

A.whenB.unlessC.becauseD.if

Answer 1

【答案】B

【解析】

句意：除非允许，否则你不应该进入教师办公室。

考查连词。when当……时；unless除非；because因为；if如果；根据句意理解可知，后句you are allowed to是前句You are not supposed to enter the teachers’ office的条件，所以这里应该用条件状语从句的连词，这里表达的是“除非”，英语是unless，，故选B。