Professor Hess says a major value of sustainable agriculture is making good use of what you have.

VOA: special.2009.04.14

And deciding how valuable it is, how good it is for me to be alive is a matter of adding up the value of the contents of the life.

它的价值，以及我活着的好处,取决于生活内容的价值总和。

耶鲁公开课 - 死亡课程节选

But instead in this chemistry course, I will just tell you the solutions to differential equations. And what we can do is we can start with some initial value of r, and here I write r being ten angstroms. That's a good approximation when we're talking about atoms because that's about the size of and atom.

但在这个课里，我会直接，告诉你们微分方程的解,我们可以给距离r一个初始值,我这里把r取10埃,当我们讨论原子时,这是一个很好的近似,因为原子的尺寸。

麻省理工公开课 - 化学原理课程节选