这是因为您不能为抽象类型创建工具。

This is because you cannot create tooling for abstract types.

youdao

另一个派生的示例是使用不带抽象类型的扩展。

Another example for derivation is when you use an extension without an abstract type.

youdao

包含它的类型于是也是一个抽象类型。

The enclosing type is then itself abstract.

youdao

I'm going to define a class, and in particular, what I'm going to do, is walk through what that says.

我们碰到了一个问题，这个问题就是，我们想要建立，一个抽象数据类型。

麻省理工公开课 - 计算机科学及编程导论课程节选

And over the next couple of days, you'll see what we mean by this in detail.

就是抽象数据类型，你可以在网上看到这两个术语。

麻省理工公开课 - 计算机科学及编程导论课程节选

What we're really doing, or I shouldn't say what we're really doing, a basic piece of what we're doing, when we talk about classes or objects, is we're doing something that Professor Guttag mentioned, we're defining an abstract data type.

或者我不应该，说我们真正要做的，当我谈到类或者对象的时候，我们在做的基本的东西，如Guttag教授提到的,就是定义一个抽象数据类型，那么这到底是什么意思呢？

麻省理工公开课 - 计算机科学及编程导论课程节选