英语定语从句1、He is the only one of the students who _________ a w

英语定语从句
1、He is the only one of the students who _________ a winner of scholarship for three years.
A、is B、are C、have been D、has been
2、Meeting my uncle after all these years was an unforgettable moment,_________I will always treasure.
A、that B、one C、it D、what
3、Anyway,that evening,________I'll tell you more about later,I ended up staying at Rachel's place.
A、when B、where C、what D、which
回答时希望写明原因,最好要有同类型题目的训练
我资料上的答案是A、B、D、但是我不知道是否正确与原因请各位讲明原因，最好提供一点定语从句的练习，