So we can think about something I mentioned last time, which is when we're thinking about chemistry and what's really interesting in terms of chemical reactions, it's mostly valence electrons we're talking about, those are the ones that tend to be involved in chemical reactions.

我们可以考虑一下我上次提到过的一件事，那就是如果我们讨论化学,以及什么是化学反应中,真正令人感兴趣的东西，我们讨论的几乎都是价电子，它们才是在化学反应中,真正起作用的部分。

麻省理工公开课 - 化学原理课程节选

If you know it' s going to work, it's not an experiment.

如果在做实验时,你已经知道这个成分会起作用，那这就不是一个真正意义上的实验了。

普林斯顿公开课 - 领导能力简介课程节选