这里为什么要用to which,

题目

这里为什么要用to which,
Thursday’s apology,coming at a time when the president and his administration are under intense criticism over the rollout of the health-care law,highlights the extent to which it has become a political liability for the White House.

答案

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...