Now that I've written sqrt, I can just use it anywhere I want in the code. You've got to rely on the fact that I wrote it correctly, but you can basically suppress the details of how it's used.

就是忽略细节,既然我已经编写了sqrt函数,我可以在代码的任何地方使用它，你完全可以依靠,我已经编写的这个函数。

麻省理工公开课 - 计算机科学及编程导论课程节选

You are pushing down with the weight mg, and the floor has got to be pushing up with the mg, because the spring is not going anywhere.

你向下的作用力是重力 mg,然后地面向上的支持力也是 mg,因为弹簧现在根本没动

耶鲁公开课 - 基础物理课程节选