问题
选择题
― Has Jackson finished his work today?
― I have no idea, but he ______ it when I saw him this morning.
A．had done
B．would do
C．was doing
D．would have done
答案
答案：C
考察时态.句意:今天杰克逊已经完成了他的工作吗?——我不知道，但是当我今天早晨看见他时他正在做。结合语境可知下文描述的是在过去某个时间正在进行的动作，故用过去进行时态。选C。