Question

超简单英语问题！

After working on the maths problem for hours ,he found ___ he thought was the key to it.

A.what B.that C.where D.which

一定要说出为什么！！！

Answer 1

A what 宾语从句里面缺少一个主语，where引导壮语从句，不选，that只是单纯的引导，没办法做主语成分，which可以代指主句中的某个东西，在从句中充当成分，但是这个主句中没有可以代指的成分，所以选what，即 the thing which

Answer 2

A

what引导宾语从句

不要受he thought 的影响，he found what was the key to it
“他找到了这个题目的答案”

Answer 3

B
where 与WHICH引导状语从句，不行
WHAT引导名词状语从句，不行。

只能用能引导宾语从句的THAT。

Answer 4

A