Nobody knows the reason why he is often late for school.把why改成that/which引导的定语从句
问题描述：
Nobody knows the reason why he is often late for school.把why改成that/which引导的定语从句
答
Nobody knows the reason for which he is often late for school
友情提示：此类题 where=in which why=for which
答
Nobody knows the reason in which he is often late for school.
望采纳、原创哦~~
答
Nobody knows the reason 【for which】 he is often late for school
或许你可以这么考虑：for是“为”,which是“什么”,组合就同等替代了why“为什么” .