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对了。陈启安装好后，简单玩了一下，发觉比他想象中的还要略好一点。If he asks different questions every time, perhaps his understanding of English has made little progress or even no progress at all.In the previous example of electric lights, a state mode program was completed. First, the Light class is defined, which is also called Context here. Then in Light's constructor, to create instance objects for each state class, Context will hold references to these state objects in order to delegate the request to the state objects. The user's request, that is, the action of clicking button, is also implemented in Context, with the following code:Since Pizza is still an abstract class, when we create a subclass of FactoryPizzaStore, we should also implement a specific subclass inherited from Pizza. If we only create a subclass of FactoryPizzaStore without a corresponding subclass of Pizza, what does our pizza shop sell?Mobile phone address book memos, operating system backup points, database backup, etc. in life are all applications of memo mode. Memorandum mode captures the internal state of an object without destroying the encapsulation and saves the state outside the object, so that the object can be restored to its original state later. The specific structure diagram is as follows:1. Download a Google Earth software and enter Google Earth.