the reason why和the reason that 区别
the reason why和the reason that 区别 具体解析如下：
可用the reason why, the reason that, the reason for which, the reason
Do you know the reason she cried? （通常省略why或that）
Do you know the reason why she cried?（why比that更常用）
Do you know the reason that she cried? （that比why正式）
There are several reasons why I don’t like him.
2.定语从句中，the reason 作先行词，关系词作主语、宾语、表语时，不用why，用that或which
The reason that/which she gave us was ridiculous.
3.同位语从句中，the reason that +原因本身（that通常不省略）
We couldn't attend the event for the reason that it was raining heavily.
（that it was raining heavily是reason的具体内容）