And so there are only two kinds of waves that can exist on this violin string, standing or traveling.

由于这只有两种波,可以存在在这条弦上，驻波或行波。

麻省理工公开课 - 固态化学导论课程节选

Someone might also say, you know a little inequality, even a substantial inequality, is not so bad as long as nobody is really suffering.

有些人也可能会说，微小的贫富差距，甚至显著的贫富差距存在，只要没人觉得痛苦就行了。

耶鲁公开课 - 金融市场课程节选