语法分析阶段的主要任务是组词成句。每一种语言都有一组文法。按照这些文法，可以由单词组成语法单位，如短语、语句、过程和程序。语法分析就是通过语法分解，确定整个输入串能否构成语法上正确的句子和程序等。-The main task of the parsing stage is a group of words into a sentence. Each language has a set of grammar. These grammars can be composed by the word