When I came back yesterday evening my brother his homework.A. is doing B. has done C. wa

问题补充：

When I came back yesterday evening, my brother his homework.

A. is doing B. has done C. was doing

答案：

解析：句意：当我昨天晚上回来的时候，我的哥哥正在写作业。when引导的时间状语从句，强调在某一时刻，主句经常用进行时，根据该句的时间，故用过去进行时，故选C。