the reason for his success is _____ he worked hard

Question

a. why b. that c. because d. for
为什么选b？语法分析下

Answer 1

首先要确定好，这句话是主系表结构，the reason for his success 是主语，is是系动词，is后面很明显是个从句了，而且这个从句的功能就都是当表语了。所以that从句是作了表语的，并且表语从句用that引导就行。Why放进去，译不通，because与reason重复了，for也不可能。

Answer 2

补充一句，要是想把because和why 用进来，可以这样说这句话：1、The reason why he succeeded was that he worked very hard.这句也是个主系表结构：The reason why he succeeded是主语，was是系动词，that还是引导表语从句。还要注意，这句很像题目的原句，原句for是介词，后面要加名词。2、另外就是：It was because of his hard work that he succeeded.这句是强调句，顺过来,就是正常语序下可以说：He succeeded because of his hard work.这句的结构是：He succeeded 是个普通的主谓结构，而且这就完整了，后面because of+短语，是对“他成功了”补充了一个原因状语。

Answer 3

选b
翻译是 他成功的原因是他努力工作
相应的成分都有了，“he worked hard”就是原因，所以用that从句

Answer 4

侧重于原因，加强语气。。

Answer 5

非定于从句只能用that和what。