我的参考书上有这样一段话：

我的参考书上有这样一段话：
先行词是表示时间的time,day等和表示地点的place,house等时,一定要注意分析从句的结构,如果缺少主语或宾语时,关系词应该用which或that,缺少时间状语或地点状语时,才能用when或where.
还有下面几个句子：
I"ll never forget the day when my hometown was liberated.
I"ll neve forget the days which/that we spent together last winter.
哪里缺少主语或宾语、时间状语或地点状语了?哪位大侠能指点一下究竟什么时候用which\that\when\where.
还有下面几个定语从句练习：
1.They want to develop a kind of dog-friendly food _____will help dog owenrs cool down their pets.
A.who B.what C.which D.whether
2.We used to study in the old building____was broken down last year.
A.which B.where C.what
3.Have you found the information about the famous people______you can use for the report?
A.who B.what C.whom D.which
我仍然不是很明白，但至少比以前要好。我会继续努力的。十分感谢3楼wangmumu1024 打了那么一长段，但我更能理解1楼的方法，也很感谢2、4楼。