英语超简单一小句关于定语shereceivesaletterfromherboyfriendeveryday.这句补齐了之后,出现的which是怎么分析出来的呢from前有必要加which吗?哪位高手帮忙讲解下谢谢shereceivesaletterwhichisfrom

　　英语超简单一小句关于定语

　　shereceivesaletterfromherboyfriendeveryday.

　　这句补齐了之后,出现的which是怎么分析出来的呢from前有必要加which吗?哪位高手帮忙讲解下谢谢

　　shereceivesaletterwhichisfromherboyfriendeveryday.