So a closed system would be, for instance, a glass of ice water with an ice cube in it, with the lid on top.

因此闭系可以是，比如说，一杯放了,一个冰块的冰水，顶上加了盖子。

麻省理工公开课 - 热力学与动力学课程节选

You don't need to know those, but just because it's a special case with the hydrogen atom, they do tend to be named -- the most important, of course, tends to be the Balmer series because that's what we can actually see being emitted from the hydrogen atom.

你们不需要记住,但因为这是氢原子的特例,人们想要命名它，最重要的是当然是Balmer系,因为它是我们可以看到的,从氢原子放出来的光谱。

麻省理工公开课 - 化学原理课程节选