n.成熟；老成

His behavior is not particularly adult. 他的舉止行為還不太成熟。

His behaviour is not particularly adult. 他的舉止行為還不太成熟。

She's doing a project on adult education. 她正在進(jìn)行一項(xiàng)有關(guān)成人教育的研究。

He'd spent all his adult life in the army. 他的成年生活全是在軍隊(duì)里度過的。

They enjoyed stories about adult naughtiness. 他們喜歡有關(guān)成年人頑皮的故事。