reason后面的why能省略吗

ThatsoneofthereasonsWHOishavingthis meetingtoday.

reason后面是否省略了why呢，why不是不可以省略吗？

是的，这个why可以省略。关系副词why用于the reason后引导定语从句常可换成that或for which，均可省略。比如：

Thats the reason he came. 这就是他来是什么原因。

又如：

The reason she was ill was that she had eaten bad meat. 《现代英汉词典》

The reason I called was to ask about the plans for Saturday. 《朗文当代英语词典》

The reason these cars are so expensive is that they are largely built by hand.《麦克米兰英语词典》