They can reproduce and so you only need to give a few of them in order to make many, many inside the body.

它们能自我复制,所以只需少量病毒,就能在体内产生大量的病毒

耶鲁公开课 - 生物医学工程探索课程节选

It's just like, we get to meet so many people that we're going to need to know in the future.

就像，我们可以见到很多将来需要认识的人。

认识更多人 - SpeakingMax英语口语达人

You need to know if it's an equilibrium, and you also need to know how many components you have in your system So, a glass of ice water with an ice cube in it, which is a heterogeneous system, has only one component, which is water, H2O.

要知道它是不是平衡的，你还需要知道,你的系统中有多少组分,一杯放了冰块的水，虽然它是个非均匀系统，但它只有一种组分，那就是水。

麻省理工公开课 - 热力学与动力学课程节选