Question

— 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

Answer 1

C

解析:

根據(jù)后面時(shí)間狀語this morning可判斷為過去時(shí)，排除B；進(jìn)行體表示“示完成性，暫時(shí)性，感情色彩”。結(jié)合上句，不知道Sam是否做完，所以C 項(xiàng)是最佳答案。