I will never forgert the day_____I joined the League.为什麽填when而不填that,这是什麽从句?

问题描述:

I will never forgert the day_____I joined the League.
为什麽填when而不填that,这是什麽从句?

when

因为that是关系代词,要充当成分但后面的从句是完整的不缺少成分,所以要用关系副词when.
这是时间状语从句~