So people change-- up or down in their level of happiness is a result of their experiences.

人们的快乐水平会上下变化,这是他们的经验之谈。

哈佛公开课 - 幸福课课程节选

So, if you use a black lamp or something and you excite something up to a higher energy level and then it relaxes back down to its lower energy state, it's going to emit a new wavelength of light, which is going to be visible to you.

如果你用一个紫外灯或别的,东西把某种分子激发到,更高的能级，然后它会掉回,到低能级，它就会释放,一个新的波长的光,这个光是可见的。

麻省理工公开课 - 化学原理课程节选

because all we konw now it's orange alert, the alert level has gone up or gone down We don't really know what it goes on behind the scene.

我们都知道现在是橙色警报，警戒线时高时低,我们真的不知道,事情背后是如何处理的。

普林斯顿公开课 - 国际座谈会课程节选