I don't quite know the reason _______ made me think over and over

问题描述:

I don't quite know the reason _______ made me think over and over

which/that

这是一个定语从句,the reason 是先行词,在定语从句中做 主语.

这个题 容易 错填 why ,如果填了 why 定语从句没有主语,句子就不成立了.