It's just minus the sum of all these things, because of course these are just defined as the work done by the environment to the system.

等于负的这些东西的和，因为它们的定义是,环境对系统所做的功。

麻省理工公开课 - 热力学与动力学课程节选

And what's important to keep in mind about formal charge is if we have a neutral atom, such as we did in thionyl chloride here, the sum of the individual formal charges on individual atoms within the molecule have to equal 0.

而关于形式电荷记住一点是很重要的,那就是如果我们有一个中性原子，比如亚硫酰氯，那么这个分子中的所有原子的,形式电荷之和应该等于零。

麻省理工公开课 - 化学原理课程节选

When I give you multiple of i and another multiple of i, there's some has got as its coefficient the sum of the two coefficients.

如果我给你两个不同 i 矢量的倍数,就可以得到某个矢量,且它的系数是这两个系数的和

耶鲁公开课 - 基础物理课程节选