定语从句关系代词1.Iwillneverforgettheday_Imetyou.2.Iwillneverforgetthedays__wehad1.Iwillneverforgettheday_Imetyou.a.whenb.onwhichc.thatd.不填四种答案都可以可是2.Iwillneverforgetthedays___

　　定语从句关系代词1.Iwillneverforgettheday_Imetyou.2.Iwillneverforgetthedays__wehad

　　1.Iwillneverforgettheday_Imetyou.

　　a.whenb.onwhichc.thatd.不填

　　四种答案都可以

　　可是2.Iwillneverforgetthedays_______wehadagoodtimetogetheratthesea.

　　只能填when和inwhich

　　为什么句2不可以填that或是不填呢?

　　两句有什么区别?