where引导的定语从句 ,where修饰works,作它的地点状语=in which (in the factory)
切记：where引导的定语从句 ,where 作定语从句中谓语动词的地点状语This is the reason why he was late. 句中why引导定语从句，why在从句中作原因状语吗？作谁的原因状语呢？the reason why he was late. 句中why引导定语从句，why在从句中作was late的原因状语why=for whichThis is the reason why he was late( he was late for the reason)