我对自己写出这么幼稚的东西感到羞愧。I'm ashamed of the babyish nonsense I write.我们终于对他幼稚的行为忍无可忍.We eventually ran out of patience with his childish behaviour.像那样幼稚的想法可以一笑置之.A childish idea like that can be amusedly tolerated....

“幼稚的”的英语可以翻译为：naive，babyish，[医] infantile，juvenile，childish ...