问一个英语问题哈!

问题描述:

问一个英语问题哈!
I'll never forget the day ( ) we stayed in the country and the days ( ) we spent happily.
"( )"中填when 或which
顺便问一下为什么

第一个填when ,the day在后面的定语从句中做状语,由when引导;
第二个填which,the days在后面的定语从句中做宾语.