The nation's fragile public health system also is struggling to cope with a rising number of influenza cases.

VOA: standard.2009.09.14

I have shown that by taking Avogadro's number of individual ion pairs and putting them all together in a line, the system's energy became more negative.

我推导出了,从每一个离子对中抽出阿伏加德罗常数,再把它们放在一起在一列中，这个系统的能量就变得更负。

麻省理工公开课 - 固态化学导论课程节选

It's a closed system, so the number moles doesn't change.

这是一个封闭系统，因此摩尔量不会改变。

麻省理工公开课 - 热力学与动力学课程节选