定语从句中where的用法

请举例说明

where：当主句中的先行词是表示地点意义的名词时，它只能作其所在的定语从句的地点状语，放在定语从句的句首。如果定语从句的引导词作该定语从句的主语或宾语时，也要改用关系代词that或which来引导。例如：

　　This is the room where(＝in which)I lived last year. 这就是我去年住过的房间。

　　Is this the classroom where(=in which) the old worker is going to make/give us a report? 这就是那位老工人要给我们做报告的教室吗？

　　Let's look for a place where we can swim. 咱们找一个可以游泳的地方吧。

　　The building that is being built over there will be a new hospital. 正在那边建的楼房将是一家新医院。(引导词that作定语从句"that is being built over there"的主语)

　　That is the factory (that) they visited last month. 那就是他们上个月参观过的工厂。(引导词that作定语从句"(that) they visited last month"的宾语，that可以省略)

where 是一个先行词在从句中作状语