Is she your younger sister?

这个是你妹妹吗？

youdao

Is your younger sister a college student?

你妹妹是大学生吗？

youdao

Is your sister older or younger than you?

你的姐妹比你大还是小？

《牛津词典》

My younger sister. Look at your dirty face.

我的小姑子呀，你看这小脸花的。

youdao

My younger sister. Look at your dirty face.

我的小姑子呀，你看这小脸花的。

youdao