I don't know the reason why he did't come to the meeting yesterday morning.为什么不可以用that引导
问题描述：
I don't know the reason why he did't come to the meeting yesterday morning.为什么不可以用that引导
那这句怎么解释The reason that (why)he missed the train is that he got up late.
答
the reason 表原因理由做先行词时只能用why 来引导
那就补充一下吧
楼主后给出的哪个句子中的是定语从句,用that ,因为此时不表示理由了,只有在表示理由的时候才可以用why