关于定语从句,为什么要用with which,这个定语从句先行词是什么?

问题描述:

关于定语从句,为什么要用with which,这个定语从句先行词是什么?
One of the most signifcant aspects of most of these studies of genius is the frequency with which early encouragement.

定从缺谓语 应该是 with which early encouragement had effect
先行词是the frequency
with which引导定语从句 并作定从中的方式状语
也就是
early encouragement had effect with the frequency