And, when zinc sulfide is hit by particles or by anything, by radiation or by particles of greater than a certain critical energy, there is a glow.

当粒子或其他东西,通过辐射或粒子的方式，并且能量高于临界值,撞击到硫化锌的表面上的时候，就会发光。

麻省理工公开课 - 固态化学导论课程节选

As we increase the voltage, we get to a critical value at which it is possible to actually draw electrons across the gap.

当我们增加气压时，我们得到了一个临界值，在这个临界值上,将电子吸引过来是完全有可能的。

麻省理工公开课 - 固态化学导论课程节选

We'll think about it in section, how you don't need to vaccinate everybody, but you just need to vaccinate a critical number in order to stop the disease from progressing through a community.

我们在讨论会上讲这个,为什么不需要给每个人都接种,但你只需要让接种人数达到一个临界值,就能阻止这个疾病在社会中传播

耶鲁公开课 - 生物医学工程探索课程节选

There are more people who can work to increase the production, but beyond that point there are more people to feed than the production can produce, and that leads to a desire for expansion of the land available for cultivation.

越来越多的人从事工作,生产力得以提高,但是一旦突破临界值,花费就要超过所得了,它导致了对土地扩张的需求

耶鲁公开课 - 古希腊历史简介课程节选