我有个弟弟，他业余时间做乒乓球教练。（只有这一个弟弟）

I have a brother, who works as a part-time table tennis coach.

youdao

我的弟弟读小学四年级，他只有10岁。

My brother is in Grade Four. He is only 10 years old.

youdao

我的弟弟个子矮——只有一米五十。

My brother is a short man-he's only 1 m. 50.

youdao

我的弟弟个子矮——只有一米五十。

My brother is a short man-he's only 1 m. 50.

youdao