Unless it is a bit-field (9.6), a most derived object shall have a non-zero size and shall occupy one or more bytes of storage.
除非作为位域(9.6)，最终派生对象总是具有非零大小并总占用一个以上字节的存储。
The object model supports multiple interfaces: Instead of having a single most-derived interface, an object can provide any number of interfaces.
对象模型支持多接口：对象可以提供任意多的接口，而不是单一的最终接口。
One of the most important things you do with such a family of classes is to treat an object of a derived class as an object of the base class.
你对这个家族类能做的最重要的一件事就是把衍生类当作一个基类去对待。
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