问题补充:
—Why didn’t you go to play football with us yesterday afternoon?
—I my mother with the housework then.
A. helped
B. was helping
C. had helped
D. have been helping
答案:
A. helped
(答案→)B. was helping
C. had helped
D. have been helping
解析:过去进行时的用法。句意:-昨天下午你为什么不和我们去踢足球呢?-那时我正帮我母亲做家务。表示过去的时间正在做某事,用过去进行时。故选B。