几道定语从句问题1.There is a mountain----the top is always covered w

几道定语从句问题
1.There is a mountain____the top is always covered with snow.
A.of which B.whose C.its D.that
2.－Do you know our town at all?
－NO,this is the first time ____ I ____ here.
A.that,was B./,have been C.that,came D.which,am coming
3.That old man had three sons,all of____ died during the last earthquake.
A.them B.which C.whom D.that
4.Please tell me the way ____ you did the job.
A.how B.where C.which D.in which
5.I'll always remember the day ____ I joined the party.
A.in which B.in that C.why D.when
6.This is the room ____ we often have breakfast.
A.which B./ C.in which D.that
请分析一下解题思路（选这个答案的原因）