《illustrate c#2008》：
Inheritance allows you to define a new class that incorporates and extends an already declared class.
继承允许你定义一个新的类。这个新的类---包含并且扩展原来已经存在的类。
• You can use an existing class, called the base class, as the basis for a new class, called the
derived class. The members of the derived class consist of the following:
– The members in its own declaration
– The members of the base class
你能够使用一个已经存在的类，这个已经存在的类叫做基类。这个已经存在的类是新类的基础、基本。这个已经存在的类派生出一个新类，这个派生出来的新类叫做派生类。这个由已经存在的类也叫做基类派生出来的新类也就是派生类，里面的成员由以下组成：
---这个由已经存在的类也叫做基类派生出来的新类也就是派生类中，声明的成员
---这个由已经存在的类也叫做基类，的成员
• To declare a derived class, you add a class-base specification after the class name. The class-base specification consists of a colon, followed by the name of the class to be used as the base class. The derived class is said to directly inherit from the base class listed.
为了声明一个派生类，你加入一个基类的"specification”在类名字的后头。这个基类的"specification”其实一点也不神秘，它由一个“结肠”，并且followed by 类的名字，这个类的名字说穿了就是基类。“结肠”？也就是冒号。
• A derived class is said to extend its base class, because it includes the members of the base class plus any additional functionality provided in its own declaration.
一个派生类被说成是扩展了基类，原因就是派生类include基类的原来的成员，而且还包括额外的函数（这些都有老子我自己定义。）
• A derived class cannot delete any of the members it has inherited.
一个派生类不能删除基类的任何成员。
For example, the following shows the declaration of a class called OtherClass, which is derived from a class called SomeClass:
例如：下面就shows了一个新类的声明，这个新类我们命令它的名字叫做"OtherClass",这个"OtherClass"是被派生于一个类，这个类叫做"SomeClass”:
Class-base specification
↓
class OtherClass : SomeClass
{ ↑ ↑
... Colon Base class
}
这个图可以看出，先前的Class-base specification他妈的就是 “: SomeClass” ，由大肠Colon+基类Base class组成。
