If we build an engine for a car or anything else, it almost always is going to have some key element that's operating in a cycle, otherwise it won't keep going, right.

如果我们为一辆汽车，或其他什么东西制造一台引擎,它总要有一些关键，要素来形成循环。

麻省理工公开课 - 热力学与动力学课程节选

For example, they help us think beyond what we are thinking right now, broaden our thinking; they help us build relationships; they help us build capacities-- remember one of the key concepts of this course is the positive emotions, positive psychology as a field as a whole, is about building capacities.

比如它们有助我们超越,现在的思考范畴，拓展我们的思想;,有助我们建立人际关系;,帮助我们建立能力-,这门课的一个主要概念,就是积极情绪，积极心理学，就是要建立能力。

哈佛公开课 - 幸福课课程节选