We need to make sure that all Americans, not just the folks who happen to work on Wall Street, feel that we are digging ourselves out of the hole,"

VOA: standard.2009.12.05

No, we call that work positive work. All right, so that means we need to put a negative sign right here, by convention.

历史上有过不同的习惯，这里我们规定,如果环境对系统做功。

麻省理工公开课 - 热力学与动力学课程节选

So all we need to find out is the work now.

所以我们现在需要知道的。

麻省理工公开课 - 热力学与动力学课程节选