We can go back and forth between these two equilibrium states They're connected.

我们可以,在这两个平衡态间往返,它们是相互联系的。

麻省理工公开课 - 热力学与动力学课程节选

how can we move between different parts of the city?

我们还能怎样往返于旧金山不同的地方呢？

旧金山的公共交通 - SpeakingMax英语口语达人

So the problem here, roughly, is given, a number of cities, and say the cost of traveling from city to city by airplane, what's the least cost round trip that you can find?

基本上就是一个这样的问题,你被告知了一些城市,以及在城市之间坐飞机旅行的花费,那一条是你们能找到最短往返路径？

麻省理工公开课 - 计算机科学及编程导论课程节选