英语问题

1.The reason why
2.The reason is that...
这是常用的带reason的结构.
第一个the reason是先行词,如果先行词在从句当状语的话,用why, 如果不是当状语,而是其它句子成份,则用相应的关系代词. 如:The reason why he didn't come was that he was ill then.他没来的原因是他当时病了.why在从句中当没来的原因.
The reason that he gave me was that he was ill then. 这句中的reason在从句中当give宾语,所以用that或which.
第二个结构是引导表语从句.就是你提出的这个句子,is后面是表语,从句子意思已经完整,所以用that引导从句.
The reason is __________ he is unable to operate the machine.
A. because B. why C. that D. whether
所以选C.

问题英文

The reason is _____c_____ he is unable to operate the machine.
A. because B. why C. that D. whether
答案解析：答案为C 答案

表示具体理由用 这样句型：The reason is that sb do sth

选C。
后面的he is unable to operate the machine这是原因，所以不用why。

wether不用再表示原因的表语从句。
because与reason 意思重复
选that，这是that引导的表语从句。

正解C
考察表语从句， 从句是个完整的陈述句， 故用 that 引导
原因是他不会操作机器。