Models need to be developed where we work closely with parterner institutions and schools , where institutions reciprocally exchange pre-service teachers in local schools, and where local teachers are engaged as both participants and hosts.

译文：模式需要改进，因此我们需要与合作机构及中小学密切合作，各机构相互交换当地学校的职前教师，而当地教师也可作为参与者和东道主参与其中。

问：该句中句子结构：“主句＋3个where引导的从句”，可是从句却被译成“因为”，wherer这里不是引导的都是定语从句么？先行词为Models，怎么译成了原因状语从句？©