请翻译成英语：他有一个年轻的弟弟。

He has a young brother.
younger 是比较级， younger brother 才是弟弟
young 是指 年轻的意思。
看来年轻的意思如 looks young

brother 有大有小，这 brother 可以是哥哥 (elder or older brother)， 或是 弟弟 (younger brother)

所以不能把年轻的弟弟翻译为 young younger brother !

他有一个年轻的弟弟
可以说： His younger brother looks young.

当然说成 She has a young younger brother 是怪怪的

He's got a young brother.

He has a younger brother

He has a young brother.

This is his younger brother。

He has a little brother.
不可以这么说