Question

I decide which room is to live in为什么不对?把他看做which引导的宾语从句嘛.

Answer 1

这句话不对,应该是“which room to live in”.

“which room”是宾语,加上“to do”结构,相当于一个名词.语法上叫“动词不定式作宾语”.

我来决定住哪间房子.

又例如：I don't know what to buy.（我不知道买什么.）

可以理解了吗?

PS：你说的“把它看做which引导的宾语从句嘛.”

那这句话应当是这样的：“I decide which room I should live in.”