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于是，丫头们便飞奔出去，分头往各院去取乐器。个子倒也不算矮，肤白细嫩，桃腮，柳眉弯弯，水润的圆眼，挺巧的小鼻子正对着纤巧的尖下巴。你为一己名利气节，决议葬送全军将士皇室一族么？。它见板栗表哥少年英姿、俊秀不凡，掳回洞去做女婿就麻烦了。现在形势本来就不妙，霸王是否该遵从亚父的遗言，依计行事呢？项羽终于眉头一动，有些动容了。The Liskov Substitution Principle (LSP) is one of the basic principles of object-oriented design. The Richter substitution principle says that wherever a base class can appear, subclasses can certainly appear. LSP is the cornerstone of inheritance reuse. Only when derivative classes can replace base classes and the functions of software units are not affected can base classes be truly reused, and derivative classes can also add new behaviors to base classes. The Richter substitution principle is a supplement to the "open-close" principle. The key step to realize the "open-close" principle is abstraction. The inheritance relationship between the base class and the subclass is the concrete realization of abstraction, so the Richter substitution principle is the specification of the concrete steps to realize abstraction. --From Baidu