NASA officials cleared the flight after technicians fixed a hydrogen leak in the shuttle's fueling system, which delayed the launch from last week.

VOA: standard.2009.03.15

All I have done is said I have a fixed system here.

我所做的说明我得到一个固定的系统。

麻省理工公开课 - 固态化学导论课程节选

So, and of course, you know, keeping entropy as a fixed variable for a system like that is extremely cumbersome.

所以，对这样的系统要求它们的熵保持恒定,和一个非常笨拙做法。

麻省理工公开课 - 热力学与动力学课程节选