look up,look into ,look for 加代词在什么情况下放在中间?

问题描述:

look up,look into ,look for 加代词在什么情况下放在中间?
如 look it for 怎么又有look for you
那look you up you 是代词呀

只有look up可以中间放代词.其他都不可以