Linear equation means that solutions are additive.

线性方程的结果是可加的。

麻省理工公开课 - 固态化学导论课程节选

The other two you know are stuff you can add, and you know where you're adding those things, because the particle has a head start.

另外两项是可加可不加的,而且你也知道这两项是怎么来的,因为质点运动是有起点的

耶鲁公开课 - 基础物理课程节选

I am going to do that by adding an electron.

加一个电子可实现这一转化。

麻省理工公开课 - 固态化学导论课程节选

We are able to talk about the fact that two plus one equals three, but it's not as though we ever come across numbers-- number three itself--anywhere in the empirical world.

我们可与去探讨,二加一等于三的这个事实,但是我们不可能有一天真的碰到数字,在现实世界中碰到个叫"数字三"的东西

耶鲁公开课 - 死亡课程节选