这引入了软件分析和设计中的一个常量：变更。

This introduces the one constant in software analysis and design: change.

youdao

类变量同样需要小心使用，但它们又恰恰是引入下一部分要讨论的常量命名的最好工具。

Class variables must also be used with care, but they are precisely the right tool for introducing names for constants, as discussed in the following section.

youdao

在PHP V5.3中引入的名称空间是为php类、常量和函数提供上下文的一种方式，从而可以将使用相同名称的元素看作是惟一的。

Namespaces - introduced in PHP V5.3 - are a way of giving your PHP classes, constants, and functions context so that elements with the same names can be understood as being unique.

youdao

We introduced a feature of C called a constant, but how many quizzes did I assume every student has?

我们引入一个C的特性，叫做常量，但是我能假设每个学生做了多少测验呢？

哈佛公开课 - 计算机科学课程节选