She had just finished her homework her mother asked her to practice playing the piano yest

问题补充：

She had just finished her homework her mother asked her to practice playing the piano yesterday.

A. when

B. while

C. after

D. since

答案：

(答案→)A. when

B. while

C. after

D. since

解析： 考查固定结构。had just done sth when…某人刚刚做了某事，这时。。。句意：昨天她刚写完作业她妈妈就让她练习弹钢琴。选A。