If you want to make sure both conditions are true and they both have to be true for any code to be executed, use ampersand ampersand.

如果你想保证两个条件都成立,或者它们两个都必须为真值，才能执行一些代码，那就使用“&&“

哈佛公开课 - 计算机科学课程节选

One of the inputs to the problems we're gonna be working on this semester and if you continue on in this world how much thought it takes to implement something, how much time it takes to run something, how much space it takes to run something?

我们将在本学期集中探讨这些问题,或者在课程之后你们也可以继续研究,为实现一些功能要有多少想法，在运行过程中又将花费多长时间，需要多大的空间？

哈佛公开课 - 计算机科学课程节选