核心问题 1
《无敌英语语法》(高中版)(海豚出版社,p.270)说:
“一般来讲在定语从句中只要先行词是 the reason, 它的关系副词就是 why, 但是在口语中, 也和 when 一样, 关系副词 why 也常被 that 代替, 也可以省略。” the reason why 和 the reason that 究竟哪个是口语用法?
词典解答 1
the reason why 为口语用法(非正式语体用法), 见 the reason why/that , that(adv.) 。the reason why/that
核心问题 2
The reason why we use oxen is that we can't afford to buy a tractor. 请问 why we use oxen 是什么类型的从句？
词典解答 2
它是定语从句，见 appositive clause or attributive clause。