Which 在从句中承担主语,谓语,当句子成分缺少时用which
where在从句中做地点状语,既句子成分完整,主谓都不缺
in which=where或when 可以替换 是将介词提前的一种用法能说的再详细一点吗定于从句的三要素就是：先行词，关系词以及关系词在从句中做的成分。which和where之间的区别就在于他们在从句中所占的成份不同。主句+先行词+where +从句主语+从句谓语+从句宾语作地点状语主句+先行词+which+从句谓语+从句宾语 或者 主句+先行词+which+从句主语+从句谓语作从句的主语或谓语所以在分析如何使用时，首先看从句是否缺少成分就可以了，不要从字面意思看There is a park which was on fire last night.There is a park where I alwaysplay with my friend 或者There is a park in which I always play with my friend. ( play in the park)