他对于他的年龄来说显得相当成熟。

He appears quite ___mature for his age.

在大学里，我希望能遇到成熟且有责任感的同龄人。

In college, I hope to meet ___mature and responsible peers.

她对危机的成熟反应给所有人留下了深刻印象。

Her ___mature response to the crisis impressed everyone.