当reason做先行词时后关系代词用什么?

小悦鑫发问啦啊 我来答啊
reason做先行词时候后面个的关系代词有很多种情况的
1.That is the reason __that______ he can’t say.
定语从句里面的,he can';t say修饰reason,本题意思：那就是他不能说的理由
具体特定解释一下：
The reason why he could not go there was that his grades were too low.
The reason why...is that...这是特定句型,why引导定语从句,is后的用词为that,一般不用because.
The reason why she did it is that she wouldn’t let her parents feel disappointed.
该句中的why引导一个定语从句,而that引导表语从句.
(1) 句中that引导的表语从句说明主语reason的具体内容
注意以下三种结构：
① The reason is / was that clause.当主语是reason / cause时,一般不能用because或why引导表语从句,以免造成语意重复.
The reason why/for which(也可以省去) he was late was that he got up late.
他迟到的原因是他起床晚了.
②当主语是This / That时,可以由because / why引导表语从句.
He got up late.That was why he was late for class.
He was late for class.That was because He got up late.
(2)why在句中是关系副词,引导定语从句,修饰先行词reason,同时它在定语从句中作状语,此时why = for which,但要注意：关系词在定语从句中做主语或宾语时,要用关系代词that或which.
The reason why/for which(也可以省去) he was late was that he got up late.
他迟到的原因是他起床晚了.
The reason that/which/(也可以省去) he gave you was reasonable.
他给你的理由是合理的.