— Has Sam finished his homework today?　　— I have no idea. He it this morning.　　A. didB. w

问题补充：

— Has Sam finished his homework today?

— I have no idea. He it this morning.

A. did

B. was doing

C. has done

D. had done

答案：

A. did

(答案→)B. was doing

C. has done

D. had done

解析：考查动词的时态。根据this morning可知句子要用一般过去时态的某种形式，且表明今天早晨我看见他时他正在做作业，所以选B。