1、输入串应是词法分析的输出二元式序列，即某算术表达式“实验项目一”的输出结果。输出为输入串是否为该文法定义的算术表达式的判断结果。
2、LL(1)分析过程应能发现输入串出错。
3、设计两个测试用例（尽可能完备，正确和出错），并给出测试结果。
-1, input strings should be the output of lexical analysis of binary sequence, that is, the arithmetic expression of a
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