It was three o’clock he came back from work.A. sinceB. whenC. thatD. before

问题补充：

It was three o’clock he came back from work.

A. since

B. when

C. that

D. before

答案：

A. since

(答案→)B. when

C. that

D. before

解析：考查when引导的时间状语，it这里指的是时间，句意是：当他下班回家时是3点。选B。