So that a half circle, instead of calling it 180 degrees, And a quarter circle, instead of 90, It's good to know certain famous angles.

半圆,不说它是180°,四分之一圆,不叫90°,知道一些常用的角度很有必要

耶鲁公开课 - 基础物理课程节选

I look at the plate on my kitchen table, it's not perfectly round, it's got imperfections; but suddenly I start thinking about circles, perfectly round objects.

我看着我餐桌上的盘子,它不是正圆的,它不完美,但是我马上就可以想到圆圈,正圆的东西

耶鲁公开课 - 死亡课程节选

When he laughed, was witty, in a merry humor, one could scarce sees his eyes, and by and by, when he was serious and positive, he opened his eyes round.

当他笑时，他是睿智的，带有令人愉快的幽默，都看不见他的眼睛了，不一会儿，他变得严肃和积极了，便圆睁着眼睛。

耶鲁公开课 - 政治哲学导论课程节选