I was doing my homework my mother was doing some sewing. A. during B. whenC. while D. aft

问题补充：

I was doing my homework my mother was doing some sewing.

A. during

B. when

C. while

D. after

答案：

A. during

B. when

(答案→)C. while

D. after

解析：A. during在…期间 B. when当…时候 C. while 当…时候D. after在…之后；句意：当我的妈妈在缝衣服的时候，我正在做家庭作业。while 当…时候，强调两个动词同时进行，故选C