为什么可以write it down ,有时不可以write down it?类似的句子的用法请说一下.

write down的用法 write it down和write them down的区别 write dowe it和write it down的区别 write down和write的用法 write it down write it down it 为什么在down前 write it down和write down it 有什么区别? 求write it down造句 用“write it down”造句 write it down 可以写成write down it吗 有什么规律 Write it down before you forget it. write down 和write on的区别