In the 1880s --a view arose that Los Angeles was just the most wonderful place on Earth.

在19世纪80年代出现了一个观点,那就是洛杉矶是地球上最完美的地方

耶鲁公开课 - 金融市场课程节选

a perfectly spherical shell dr at some distance, thickness, d r, dr we talk about it as 4 pi r squared d r, so we just multiply that by the probability density.

在某个地方的完美球型壳层,厚度，我们把它叫做4πr平方，我们仅仅是把它,乘以概率密度。

麻省理工公开课 - 化学原理课程节选