Fans loved the special way she rolled her "r"s to create a sound like a cat.

VOA: special.2009.06.07

So I got an r- I'll do it the other way around.

我有一个右,我还是反过来吧

耶鲁公开课 - 博弈论课程节选

take the derivative of this, get the velocity vector and you notice his magnitude is a constant Whichever way you do it, you can then rewrite this as v square over r.

对这个式子求一次导,就能得到速度矢量,你会发现其模长是常数,不管用什么方法,加速度也可以写成 v^2 / r

耶鲁公开课 - 基础物理课程节选

And one common way to think about it, is to think about the value of r, or the radius, below which 90% of that electron density is going to be contained.

而通常的想法，是想象，r，的值，也就是半径的值，即有百分之九十的电子密度,都落在这个范围之内。

麻省理工公开课 - 化学原理课程节选