外观模式：提供了一个统一的接口，用来访问子系统中的一群接口。外观定义了一个高层接口，让子系统更容易使用。
The Facade pattern:provides a unified interface to a set of interfaces in a subsystem. Facade defines a higher-level interface that makes the subsystem easier to use.
相比之下，外部系统是公司与其客户群之间的接口。
By contrast, an external system serves as an interface between a company and its customer base.
我发现自己同一群群的用户和开发者一起工作，撰写用户场景，起草用户接口设计。
I find myself working with groups of users and developers to write user scenarios, and sketch user interface design.
我的意思是说，苹果凭什么要花更多的成本放一个很贵的接口在iPad上面，只是为了让一群geeks开心呢？
I think I can guess what Apple thought about putting another expensive connector into the machine just to please a few geeks.
继承最终会形成一个像大家庭一样的类群，它们都继承了同一组接口。我们用一棵反转的树形图来说明它们：5。
Inheritance usually ends up creating a family of classes, all based on the same uniform interface. We express this with an inverted tree diagram: 5.
继承最终会形成一个像大家庭一样的类群，它们都继承了同一组接口。我们用一棵反转的树形图来说明它们：5。
Inheritance usually ends up creating a family of classes, all based on the same uniform interface. We express this with an inverted tree diagram: 5.
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