这里为什么要用to which,
1个回答

最简单的方法是从

the extent to which it has become a political liability for the White House.

的问句开始,

这个句子的问句是

To what extent has it become a political liability for the White House?

句子的倒装形式就是

the extent to which it has become a political liability for the White House.

(倒装句 不用 to what ,而必须用 to which .)

再举两个类似例子:

In what way is the invention useful?

倒装形式:

The way in which the invention is useful is ...

On what grounds are you justifying this action?

倒装形式:

The grounds on which I justify this action are ...

这是弄清楚短语

to which,in which,on which 等等

的用法的唯一方法.