关于reason的从句

定语从句的格局是：名词 + 关系词 + 句子
如果名词在后面的句子中做某个句子成分，多半是主语、宾语、定语、状语或表语，如果reason that + 句子，那么reason 就是在后面句子中做主语、宾语.
例如：
the reason that was given by his mother 做主语
the reason that I told you 做宾语

如果 reason why + 句子,那么 reason 就是在后面句子中做状语,表示原因=for which
the reason why he was late = the reason for which he was late.
所以,选用定语从句前面关系词的关键是两点,一是前面的名词是什么内容,是人还是物,时间、地点还是原因的名词，二是判断前面的名词在后面的句子中做什么成分

That是关系代词 Why我记得是关系副词 - -。

好像是跟限制性定语从句和非限制性定语从句有关么。
非限制性定居从句用why.限制性定语从句用that
对于限制性和非限制性我们老师解释的是从句主句之间有个逗号的就是非限制性。

好像是这样的。- -，，，

that为关系代词，说明reason在后面的定语从句中做成分
eg.I don't believe the reason he explained to me.
why 是关系副词，reason在定语从句中不做成分，即从句是完整的
eg.That's the reason why he's late for school.