I first met your sister ten years ago when she at a supermarket as a salesgirl. A. has wo

问题补充：

I first met your sister ten years ago, when she at a supermarket as a salesgirl.

A. has worked

B. had worked

C. was working

D. had been working

答案：

A. has worked

B. had worked

(答案→)C. was working

D. had been working

解析：过去进行时的用法：过去某个时间点或者时间段正在发生的事情。“十年前我初次见到你姐姐的时候她在一家超市当服务员。”选C。