The Mirror Image and Session Facade patterns are useful for changing actors in use case diagrams into valid abstractions in class diagrams, which ultimately results in a cleaner translation to code.
对于将用例图中的参与者转换成类图中有效的抽象，镜像映象模式和会话虚包模式是很有用的，这样最终将能够更清楚地转换成代码。
M: In that case, I suppose I could ask the dry-cleaner to clean up the spots for the moment, and have it well pressed. You might get it back on time then.
M：如果那样的话，这样吧，我让干洗员把污点清除掉，再把它熨好，这样您明天就会准时拿到它了。
A cleaner computer will run a bit cooler, and it'll help you avoid a fire starting inside your case.
一台较为干净的电脑运行起来会更凉爽一点，它也会帮助你避免火患。
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