He regretted the days __ he wasted in the woods and when he should have studied.

问题描述:

He regretted the days __ he wasted in the woods and when he should have studied.
填THAT 为什么不是WHEN,表浪费的那些天

先行词 the days在定语从句中充当宾语啊
he wasted (the days) in the woods 在丛林中他浪费的几天
因此不能用指代时间状语的When,而用指代宾语、主语的which/that,没有which用that