it和which的用法区别在非限制性定语从句中,which做主语时,和it有何区别?wilmabecamethefirstAmericanwomantowinthreeOlympicgoldmedalsintrack,------madehermotherveryproud.A,itB,thatC,which,D,this请详细说明理

　　it和which的用法区别

　　在非限制性定语从句中,which做主语时,和it有何区别?wilmabecamethefirstAmericanwomantowinthreeOlympicgoldmedalsintrack,------madehermotherveryproud.A,itB,thatC,which,D,this请详细说明理由哦.我知道这个题的正确答案,我主要是弄不清理由!一般灌水的请远离.本人英语水平还不赖的,所以一般灌水的答案就不必要了.