But we'll explain in the week to come exactly why and when you do things like that.

但是我们将在下周精确地解释为什么,什么时候我们那样做。

哈佛公开课 - 计算机科学课程节选

But we all know that the reason things come to a halt when you push them is, there eventually is some friction or drag or something bringing them to rest.

但我们都知道,推完之后会停下来的原因就是,最后还是有某种摩擦或者拖拽,或者别的什么使得物体静止下来

耶鲁公开课 - 基础物理课程节选

So, these are two different definitions of how to think about atomic radius, but really what you find when these are measured is they come up with almost the identical values, so there are tables, you can look up of atomic radii and see these values, and you can trust them that, they work for both this definition and for this definition here, in most cases.

这就是,关于原子半径的两种不同的定义，但实际上你会发现按照这两种方法,测量出的值是相等的，因此有很多关于原子半径的表格，你可以通过查阅它找到这些值，你可以相信这些值，它们对于这两种定义都是适用的，在大多数情况下。

麻省理工公开课 - 化学原理课程节选

Some of you are probably going to be doctors and you don't know why I'm going to do special relativity or quantum mechanics, but you don't know when it will come in handy.

你们中的有些人可能会成为医生,但你们现在不能理解,我为什么要讲相对论和量子力学,但是说不定什么时候,你就用上了呢

耶鲁公开课 - 基础物理课程节选