It's the contrast between stress and no stress. The question becomes, well,how much stress do you need to have before you lower the stress?,".

VOA: standard.2009.04.17

How much time do you need to evaluate somebody on the five dimensions of personality?

你需要多少时间才能,用大五人格来评价一个人？

耶鲁公开课 - 心理学导论课程节选

You're asking, "How much i and how much j do I need to build the same object?"

你们会问,"需要多少倍的 i 和多少倍的 j,来构成同一个矢量呢"

耶鲁公开课 - 基础物理课程节选