So, for example, we were talking about a threshold frequency as in a minimum frequency of light that you need in order to eject an electron from a metal surface.

举个例子来说，我们谈论的临界频率是,光从金属表面逐出一个电子,所需的最小频率。

麻省理工公开课 - 化学原理课程节选

So you know that x-rays are higher frequency than UV light, for example, that means it's also higher energy than UV light, and if you think back to our photoelectric effect experiments, do you remember what type of light we were usually using for those? Does anyone remember?

你们知道，X，射线的频率比紫外光高，这意味着，它的能量也比紫外光要高，那么，请大家回想一下我们的光电效应实验，大家还记得当时我们用的是什么光源吗？,有人记得吗？

麻省理工公开课 - 化学原理课程节选

Likewise, if you provide a low margin but high frequency services like payments you must find a way to retain customers for long enough to pay multiples of your customer acquisition cost.

FORBES: 10 Rules For Disruptors In The Financial Services Industry

Moreover, given the frequency with which industry members run afoul of the disclosure obligations for charges and convictions, you must be aware of the events that need to be disclosed and the windows for such disclosure.

FORBES: Stockbroker Sidesteps Felony But Trips Over Misdemeanor

Given the frequency of invisible promotions and their potential negative consequences it might make sense for you to periodically look at your own job to assess unrecognized scope changes.

FORBES: Are You The Victim Of An Invisible Promotion?