问题
选择题
----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
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。