My younger brother is still at high school.
我的弟弟还在上中学。
A So, if your older brother has a baby girl, you’re her uncle!
A 那么，如果你的哥哥有个小女孩的话，你就是她的叔叔了！
B Yes, I’m her uncle.
B 是的，我是她的叔叔。
A And your younger brother? What about him?
A 你的弟弟呢？他怎么样？
B Oh, he’s much younger than me. My younger brother is still at high school.
B 噢，他比我小得多。我的弟弟还在上中学。
A So he still lives at home with your Mum and Dad.
A 这么说他仍然和你的父母住在家里。
B Yes, he’s still at home. I guess he’ll go to college next year.
B 是的，他还住在家里。我想他明年上大学。

Notes 注释
1 There are many words to describe specific relatives, e.g. uncle / uncle; aunt / aunt; nephew / nephew; niece / niece; cousin / cousin.
有很多词语可以描述具体的关系，例如uncle / 叔叔、伯父、舅舅、姨夫、姑父；aunt / 婶婶、伯母、舅母、姑母； nephew / 外甥、侄子； niece / 外甥女、侄女； cousin /表兄弟姐妹、堂兄弟姐妹
2 Remember the word still / still to describe something which someone is continuing to do, e.g. He still lives at home / He still lives at home; He’s still at high school / He’s still at high school.
记住still /仍然是用来描述某人继续做的某事。例如：He still lives at home / 他仍然住在家里； He’s still at high school /他还在上中学。

Key phrases and sentences
So, if your older brother has a baby girl, you’re her uncle!
Yes, I’m her uncle.
And your younger brother? 
What about him?
Oh, he’s much younger than me.
My younger brother is still at high school.
So he still lives at home with your Mum and Dad.
Yes, he’s still at home. 
I guess he’ll go to college next year.

那么，如果你的哥哥有个小女孩的话，你就是她的叔叔了！
是的，我是她的叔叔。
你的弟弟呢？他怎么样？
噢，他比我小得多。
我的弟弟还在上中学。
这么说他仍然和你的父母住在家里。
是的，他还住在家里。
我想他明年上大学。