And those are two things that you'd like to do with every looping construct you write: you'd like to be able to assure yourself that they will always terminate, and then the second thing you'd like to do, is to assure yourself that it does give you back a reasonable answer.

就是现在我有了能去检查程序,是不是做了正确的操作的能力：,这就是你们在写每个循环程序的时候,都要注意的两个事情：,第一件事情是要确保程序可以终结，第二件你要做的事情,就是要确保程序返回了正确的答案。

麻省理工公开课 - 计算机科学及编程导论课程节选

And in Python the expression is, operand, operator, operand, when we're doing simple expressions like this, and if I give it to the interpreter, it gives me back exactly what you'd expect, which is that value. OK?

在Python中表达式就是，运算对象，操作符，运算对象，当我们处理这样的简单表达式的时候，我把表达式传给处理器，处理器给我返回了我想要的结果，对不对？

麻省理工公开课 - 计算机科学及编程导论课程节选