当先行词是reason,且在定语从句中作原因状语时,可以用关系副词why或关系代词that,也可以省略.例如：Thereason(why/that)hefailedwashislaziness.他失败的原因是因为他懒惰.在这句话中,why引导的是

Question

当先行词是reason,且在定语从句中作原因状语时,可以用关系副词why或关系代词that,也可以省略.
例如：The reason (why/that) he failed was his laziness.他失败的原因是因为他懒惰.在这句话中,why引导的是定语从句,且在从句中作原因状语.那么that 是引导定语从句还是同位语呢?如果是同位语的话,that也是不能够省略的!

Answer 1

1.在reason作先行词的定语从句中,若从句表原因,一般用why引导定语从句,why可以用for which替换.why还可省去.
The reason why (for which) he has resigned is poor health.
他辞职的理由是健康状况不佳.
2.当reason作主语带有定语从句修饰时,其后的表语从句通常用that不用because.
The reason why he didn't come in time was that he didn't feel well.
他没有来的原因是因为他不舒服.
3.当reason用作定语从句的宾语时,引导词用that/which,而且that/which可省去.
The reason (that/which) he gave for being late was that they were held up in a traffic jam.
他给出的迟到原因是由于他们被交通阻塞给耽误了.
4.注意句型This/That's why… This/That's the reason why…
That's why he did it.(不用that代替why)这就是他为什么做这事的原因.
That's the reason why he did it.(口语中可用that代替why)