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

People in serious accidents with their paralysis as the result of the accident, very often, usually-- again, this is all the average-- go back to their base level of happiness: if they are happy before, they will be happy one year after; if they are unhappy, they will remain unhappy.

遇到严重意外的人,意外导致瘫痪，经常地，一般性的…,再次强调，这是平均而言-,都会恢复到基础幸福水平：,他们以前是快乐的，一年后，他们也会快乐;,如果不快乐，将维持不快乐。

哈佛公开课 - 幸福课课程节选