So, if you can't immediately know, and you don't all have periodic tables in front of you, so that's fine, but if you have a periodic table in front of you, you need to be able to count valence electrons, so work on that if it doesn't come naturally to you in terms of figuring that out.

如果你不能马上想到，而且你手上没有周期表，那还好，但如果你面前有一张周期表，那你就得具备从中查出价电子个数的能力，如果你不能自然而然地想到,请在这方面多下点功夫。

麻省理工公开课 - 化学原理课程节选

Yale also has an art collection, which is worth many billions, but we don't count that as part of the endowment because they will never sell it so it doesn't provide income for us.

耶鲁还有一些艺术藏品,价值好几亿美元,但我们并不把它作为基金的一部分,因为学校不会卖掉它们,所以它不会为学校提供任何收入

耶鲁公开课 - 金融市场课程节选