who is your sister?
谁是你姐姐
which is your sister?
哪个是你姐姐
第一句偏向于问名字
后一句偏向于问哪一个~就是有很多人中的其中一个能不能举个例子呢？谢谢你-who is your sister?Mary is my sister-It's your family photo.which is your sister?The girl in red is my sister