关于定语从句的题which ,where, that怎么区分

问题描述:

关于定语从句的题which ,where, that怎么区分
Coke cans are sent to a factory,_____they are smashed flat and melted and the metal things are made into new coke cans.
which ,where, that应该填哪个?
为什么呢?

选where,where在从句中充当in the factory.