1.where
This is the room where he studies.这是他学习的房间。
This is the place where he works.这是他工作的地方。
2.when
This was the day when he arrived.这是他到达的那一天。
Who knew the time when the last train came？ 谁知道最后一列火车到来的时间？
3.why
This is the reason why he went.这是他去的原因。
【提示】 why不能用于非限制从句。