问题补充:
I my homework when the lights in my room went out last night.
A. did
B. was doing
C. will do
D. have done
答案:
A. did
(答案→)B. was doing
C. will do
D. have done
解析:句意:当灯光突然熄灭的时候,我正在做作业。when 引导的从句表示一个时间点,强调在这个时间点上另一个动作正在发生。灯光熄灭是在过去,故我写作业用过去进行时,故选B。