child的形容词形式是childish；
childish：adj.孩子的；孩子气的；稚嫩的；幼稚的；天真的
相关介绍
I work hard every day for such childish behavior.
我每天工作这么辛苦，得到的竟是这样幼稚愚蠢的举动。
What we need to learn from children isn't childish.
我们要从孩子身上学的并非是孩子气。
Of course, this just makes her look more childish.
当然，这个动作只会让她看起来更加孩子气。
