— Could you please do some shopping for me Mary?— Sorry I my homework.A. doB. am doingC

问题补充：

— Could you please do some shopping for me, Mary?

— Sorry, I my homework.

A. do

B. am doing

C. have done

D. was doing

答案：

A. do

(答案→)B. am doing

C. have done

D. was doing

解析：当别人请你做某事的时候，我们表示拒绝，应该是正在做或将要做别的事，可用进行时态的结构来表示，故本题选B。意思为我正在做作业。