The sum was paid ex gratia.

这是所付的一笔特惠款。

《牛津词典》

Let x be the sum of a and b.

设x为a加b之和。

《牛津词典》

The sum of 7 and 12 is 19.

7加12的和是19。

《牛津词典》

Every president is the sum of his past experiences.

VOA: standard.2010.01.16

And he defined the average in terms of not the sum divided by two, but he chose the geometric mean.

鲍林定义平均并不是,简单相加在除以二，他选择几何平均。

麻省理工公开课 - 固态化学导论课程节选

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

But the sum and substance of his criminal career was not like a string of bank robberies.

FORBES: The demonizing of a hacker

The sum of it was a too distant cousin of the German biergarten ideal I sought.

BBC: The wiedergeburt (rebirth) of New York��s biergartens

The sum is paid by the council, which then claims the money back from the government.

BBC: Benefits system 'needs changing'