同学你好，该知识点来自沪江网校《【Uni智能】雅思7分一站式VIP-中级起点【全额奖学金签约班】》的课程，想要更系统的学习，欢迎进入课程学习。不仅可以和更多的同学一起学习，而且还有老师、助教随时的学习指导和知识点解答哦。

同学你好
the reason why ,why 代替先行词 reason 在定语从句中状语,表原因；the reason which / that , which / that 代替先行词在定语从句中主语、宾语或表语.如：
The reason why he was late is that he couldn't catch the first bus. 他来迟的原因是他没赶上第一班车.（状语）
The reason that / which he explained to his teacher is not reasonable. 他向老师解释的理由一点都不合理. （宾语）
The reason that / which is obviously right is sometimes wrong indeed. 明显正确的理由有时确是错的.（主语）

希望帮到你哦