It's reversible, that means that p external, equals p. I'm doing it very slowly so that I'm always in equilibrium between the external pressure and the internal pressure so I can go back and forth.

我都可以不损失能量，而把过程逆向进行,整个过程中的,每一步都保持平衡,现在我们来分别。

麻省理工公开课 - 热力学与动力学课程节选

For all we know, Ivan Ilyich still believes in souls, believes he's going to go to heaven and so forth.

我们都知道，Ivan，Ilyich始终相信，自己的灵魂会上到天堂。

耶鲁公开课 - 死亡课程节选

John Now, you're going to hear John and I go back and forth a lot, well I'm certainly old time, but I'm also an old time Lisp programmer.

现在，你会听到我和,来回的讲好多次，好吧我当然是个老学究，但是我也是一个老lisp程序员。

麻省理工公开课 - 计算机科学及编程导论课程节选

Does stuff change phase to go from liquid to solid and so forth, right?

物质是否从液体转变为固体,相变到底在什么位置出现？

麻省理工公开课 - 热力学与动力学课程节选

So energy can go back and forth.

所以能量可以来来往往。

麻省理工公开课 - 热力学与动力学课程节选