用递归下降分析法编制语法分析程序 对于遇到的语法错误，能够做出简单的错误处理，给出简单的错误提示，保证顺利完成语法分析过程；-Analysis prepared by recursive descent parser for syntax errors encountered, it is possible to make a simple error handling, gives a simple error, to ensure the successful completion of the parsing process