--Did Mary return late last night?--No. It was not yet 7 o’clock she arrived home.A. befo

问题补充：

--Did Mary return late last night?

--No. It was not yet 7 o’clock she arrived home.

A. before

B. when

C. that

D. until

答案：

A. before

(答案→)B. when

C. that

D. until

解析：考查时间状语从句：句意：--昨晚玛丽回来的晚吗？--不，她到家的时候，还不到7点。这里when引导的是时间状语从句，it是表示“时间”，学生容易以为是强调句，但是如果去掉it was…that这句话缺少介词，选B。