他女朋友很年轻。

Tā nǚpéngyou hěn niánqīng.

His girlfriend is very young.

你还很年轻呢！

Nǐ hái hěn niánqīng ne!

You're still so young!

她还是很年轻。

Tā háishi hěn niánqīng.

She is still very young.