-Has Tommy finished his homework yet?-I have no idea; he it this morning.A. was doingB.

问题补充：

-Has Tommy finished his homework yet?

-I have no idea; he it this morning.

A. was doing

B. had been doing

C. has done

D. did

答案：

(答案→)A. was doing

B. had been doing

C. has done

D. did

解析：表示今天上午一直在做作业。