I miss the days ___ I spent with you during last summer. The answer is when or that?

when

that 后的 I spent with you during last summer是对days 的解释说明

that引导定语从句，修饰the days.因为从句中spent后面缺少宾语，所以应该用关系代词that而不是关系副词when

that 定语从句
复位为
I spend that (the days)with -------

用that
I miss the days that I spent with you during last summer. 我很怀念去年暑假与你一起度过的日子。

本题考查定语从句，本题之所以用关系代词that，是因为它在定语从句中做spent的宾语，而关系副词when是不能做宾语的。

that
高中的时候好像经常做 这个题
当然做定语了