Think of that. And while you're thinking about it you can start reading Plato's Apology for Socrates which we will discuss for class on Wednesday.

想想这个问题，此外，你们可以开始,阅读柏拉图的《苏格拉底自辩篇》,我们将在周三的课堂上讨论。

耶鲁公开课 - 政治哲学导论课程节选

So, for example, we have this average level, and then it can go high where we have the peak, or it can go very low. We can also discuss sound waves, so again it's just the periodic variation of some property -- in this case we're talking about density, so we have high density areas and low density areas.

例如这是平均位置，在峰的位置水位高，在谷水位低，我们也可以,讨论声波它也是某种,量的周期变化，在这里我们,讨论的是密度,我们有高密度区和低密度区。

麻省理工公开课 - 化学原理课程节选