.— When did they come back last night?— It was midnight all of us were sleeping.A. thatB.

问题补充：

.

— When did they come back last night?

— It was midnight all of us were sleeping.

A. that

B. when

C. which

D. in which

答案：

A. that

(答案→)B. when

C. which

D. in which

解析：考查定语从句。根据先行词midnight为从句逻辑时间状语，可知选B。