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把那两个大木箱抬过来。悟空道人眼神幽深，身上道韵流淌，玄之又玄，玄妙不可言，与冥河教祖遥遥对峙。The ICalculator in the figure provides a unified approach,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 BaiduHttp://www.jiemian.com/article/1848914.html但是我们对越国的了解很有限……从长远看，越国的威胁不小啊。