像look it up和look through it之类的短语中的it的放置位置的依据是什么

look up和look 像look it up和look through it之类的短语中的it的放置位置的依据是什么 look up it 还是look it up look it up Look it up!翻译 look it up 和 look up it有什么区别啊怎么用? look up to和look down LOOK和LOOK UP有什么区别? put it down 与put down it 的区别,还有look it up和look up it的区别. 为什么说look it up 却说look for it 为什么说 look it up 而不说look it for look it up 和look up it 的区别?谁能帮忙解释解释啊 ? 谢了啊 look it up 像这样的词组的it在哪怎么判断 look up look up look up look up look up to和look up into有什么区别