Definition: Childish behaviour is silly, like that of a small child. Level: B2
别这么孩子气！
Don't be so ___childish!
与成年人相比，他们的争论显得相当幼稚。
Compared to adults, their arguments seemed rather ___childish.
因为一点小争执就拒绝和某人说话，这很幼稚。
It's ___childish to refuse to talk to someone after a minor disagreement.
