他意识到自己的举动很不成熟。用英语怎么说？

他意识到自己的举动很不成熟。

He knew that he had behaved childishly.

he

pron. 他，它，一个人；n. 雄性动物；

例句
Logic had prevailed and he had abandoned the idea.
最终理智占了上风，他打消了那个念头。

knew

v. 知道（ know的过去式 ），了解；

例句
She knew who to ask about finding an abortionist.
她知道向谁去打听找一个为人堕胎的。

that

det. 那个，那；pron. 那个，那；conj. 多么，如此…以至，用于某些动词、形容词和名词后，引出各种从句；adv. 不那么，那样；

例句
...expensive make-up that we saw being advertised by a beautiful model...
我们所见的由一位漂亮模特代言的昂贵化妆品

had

v. 有（ have的过去式和过去分词 ），（亲属关系中）接受，拿，买到；

例句
He claimed that his parents had abandoned him...
他声称父母遗弃了他。

behaved

v. （行为或举止）表现( behave的过去式和过去分词 )，工作，（使）守规矩；

例句
I was so badly behaved I was convinced she would be glad to see the back of me.
我的表现如此差劲，相信她会很高兴看到我离开。

childishly

adv. 天真地，幼小地，幼稚地；

例句
He hit back angrily, saying such remarks were childishly simplistic.
他愤怒地反击，说这些话太过幼稚。