----Have you finished your homework?-----No I my younger sister all day yesterday.A. was

问题补充：

----Have you finished your homework?

-----No, I my younger sister all day yesterday.

A. was looking after

B. would look after

C. had looked after

D. look after

答案：

(答案→)A. was looking after

B. would look after

C. had looked after

D. look after

解析：考查时态。句意：你完成你的作业了吗？——不，我昨天整天都在照顾我的小妹妹。可知下文 描述的是过去一直在进行的动作，故用过去进行时态，故选A。