I haven’t finished my homework yet. I my mother with the housework all day yesterday.
A. helped
B. have helped
C. was helping
D. have been helping
网友回答
A. helped
B. have helped
(答案→)C. was helping
D. have been helping
解析：考查时态。本题的关键词是all day yesterday,指在昨天一天的时间里一直在做的事情，故使用过去进行时。过去进行时既可以表示在过去的时间点，或者过去的一段时间里发生的事情，或者持续的状态。句意：我还没有完成我的家庭作业。昨天一天我都在帮助我妈妈做家务。故C正确。