He'll grow out of it.怎么翻译呀？！？

他会在其中成长

如果指阴影的话，还可以翻译成： 他会走出这个阴影。

他长大以后会就不想了,就会抛弃了.

例如

Don't worry, he'll soon grow out of wanting to be a fireman.
别担心，他不久以后长大一点就不再想当消防员了。
Don't worry too much about Sylvia's shyness with strangers, she'll grow out of it in time.
你不必担心西尔维亚在生人面前怕羞，她长大以后就会好的。