题目内容：

It was not until I got home ____ I found that I had left my keys in the office.
A.before B.when C.that D./
B为什么不对,请解析,

优质解答

It is ...that 是强调句的标志
在强调句里你把It is ...that 去掉会发现并不影响整个句子的意思.
以后做类似题要多留意that,并不是所有时间状语后都由when来引导.