Something might be short at one point and become tall at another point, ugly at one point and become beautiful-- like the ugly duckling.

一个事物可能在某一时刻很矮,然后在另一时刻又会变高,某一时刻很丑,然后变得很美,就像丑小鸭一样

耶鲁公开课 - 死亡课程节选

I'm sure there have been a quick quarrel at some point.

我确定在某一个时刻会有一些争执。

普林斯顿公开课 - 人性课程节选

At a given instant, it's got a location.

在一个给定的时刻,它在某一位置

耶鲁公开课 - 基础物理课程节选