It is necessary for explaining the concept of programming to design a small and suitable model programming language family with a clear syntactic and semantic definition.

设计具有清晰语法定义、简单合适的程序设计语言模型，对于解释程序设计语言是非常必要的。

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Chapter Three illustrates the definition of advertisement and features of language in advertisement in detail, that is, lexical features, syntactic features and rhetorical features.

第三章具体阐明了广告的定义及广告语言的特点，逐一描述广告语言的词汇特点、句法特点和修辞特点。

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