And they're useful because, first of all, they're easy to depict, they're easy to draw relatively easy once we get all the rules down.

它很有用是因为，首先，它很容易描述，它很容易画出来,一旦我们确定了所有的规则以后就比较容易。

麻省理工公开课 - 化学原理课程节选

And resonance is the idea that sometimes one single Lewis structure does not adequately describe the electron configuration around a given molecule, so instead you need to draw two different Lewis structures to describe that more appropriately.

而所谓共振态,就是有时候一个路易斯结构不足以,完整描述一个给定分子的电子排布，因此这时你需要同时画出两个,不同的路易斯结构来描述它,这样会更恰当。

麻省理工公开课 - 化学原理课程节选

So what we would like to do is to describe what the object does by drawing a graph of time versus space and the graph would be something like this.

然后我们要做的就是描述这个物体的运动,通过画一个"x-t"图,画出来的图就像这样

耶鲁公开课 - 基础物理课程节选