This was when you had this big track, and if you have wandered around different Greek cities that are dug up, some of them will have the hippodrome there, and you can see how huge they were.

里面是大型赛道，如果你参观过发掘出土的希腊城市，有一些会有赛马场，非常宏伟巨大。

耶鲁公开课 - 新约课程节选

So we keep track of the types of questions that come up, unless I said something stupid in class or been confusing, certainly.

所以我们对出现的各种各样的问题保持联系，除非我在课程上说了一些愚蠢的,或令人困惑的话。

哈佛公开课 - 计算机科学课程节选

You add them all up algebraically, keeping track of their sign, and that's the total force.

你再对这些力做代数加法,注意符号,就求出合力了

耶鲁公开课 - 基础物理课程节选

They've got an idea but they've got to fill up a track.

他们有点想法,但是他们要去填满一个音轨

耶鲁公开课 - 聆听音乐课程节选

Remember, you've got to keep track of the sign of acceleration, so if you're picking up speed towards the ground, a is negative, so it will be g plus a, but a is a negative number.

记住,一定要注意加速度的符号,所以当你加速下降的时候,a 是负的,还是 g 加上 a,但是 a 是负数

耶鲁公开课 - 基础物理课程节选