― Has Sam finished his homework today?
―I have no idea. He ______ it this morning.
A. did B. has done C. was doing D. had done
― Has Sam finished his homework today?
―I have no idea. He ______ it this morning.
A. did B. has done C. was doing D. had done
C
解析：
根据题干，语境应为“我不知道，今天早晨他还在做”，A为一般过去时，强调在过去
某一时间做某事，不强调结果；B为现在完成时，在过去发生，强调对现在的影响；C为过
去进行时，指在过去某一时间正在做某事；D为过去完成时，表达过去的过去。所以C为正确答案。