VFM: the extent to which a government, business person or consumer gets a good deal from the money which they spend on goods or services.

The extent to which 引导的是什么从句？which后面是不是省略了that呢？which后面的从句不缺成分，是不是可以由此判断出which引导的是同位语从句？

【答】首先，这不是一个完整的句子，而是一个名词性短语：the extent（程度），后面的to which...是一个定语从句，修饰这个extent。意思是：

政府、商人或消费者在商品或服务上所消费的金钱，而从中得到实惠（a good deal理解为“很大的实惠；物超所值”）的程度。

也就是说，消费者个体花了金钱购买商品或服务，从中得到实惠的程度如何。

which 之前加to，是因为to the extent（到达某种程度）的缘故。不存在同位语的问题。

先行词是the extent，后跟 to which的例句：

No one can forecast the extent to which traffic will grow.

没有人能预测将来交通流量会增长到什么程度。

She didn't realize the extent to which she had been distracted. 

她没有意识到她心烦意乱的程度。

The extent to which the Court will modify these doctrines is, as yet, unclear.

法院对这些原则修正的范围现在尚不清楚。

The extent to which women have lost their rights in Iraq is shocking.

伊拉克妇女丧失权力的程度令人震惊。