Question

l do not believe the reason ＿he was late for school 这个定语从句应该选什么关系

l do not believe the reason ＿he was late for school 这个定语从句应该选什么关系词！求解析
能不能填which或 that？

Answer 1

这里要用关系副词 why来引导 表原因。可继续参考以下，
why 指原因，在定语从句中作原因状语。
Please tell me the reason why you missed the plane. 请告诉我你误机的原因。
The reason why he was punished is unknown to us. 他受惩罚的原因我们都不知道。
I don’t know the reason why he looks unhappy today. 我不知道他今天为什么看上去不愉快。
注意：关系副词引导的定语从句经常可以用“介词+关系代词”引导的定语从句来表示。如：
From the years when / in which he was going to primary school in the country he had known what he wanted to be when he grew up. 自从他在农村读小学时，他就已经知道长大后要做什么。
Great changes are taking place in the city where / in which they live. 他们生活的城市正发生巨大的变化。
The reason why / for which he refused the invitation is quite clear. 他为什么拒绝接受邀请的原因是十分明了的。

Answer 2

reason 是修饰解释后边句子的，也就是他为什么上学迟到的原因，因此，空缺部分应该填why。

Answer 3

why
the reason why +句子， 定语从句，...的原因