I know the reason___he was unhappy at the party that day.A in which B on which C for which D that

来源：百度知道 编辑：UC知道 时间：2024/06/16 16:32:17
I know the reason___he was unhappy at the party that day.
A in which B on which C for which D that
选什么，解释？

C for which =====why为何，之所以

先行词是表示原因的名词，即reason，用why，在定语从句中充当原因状语，这时一般可以用for ＋which来代替:

I don’t know the reason why/ for which he did it.
.
The reason why/ for which he was afired was not clear.

选C
我第一反应就是填Why
既然没why，用C答案是一样的，不过好像D理解为同位语其实没多少不对。。

c
for which引导原因定语从句

选C

表原因，用FOR。

选C。相当于why.