我正在阅读5月考试的过去的论文，我不确定如何回答以下问题：
The following grammar describes a simple language of arithmetic expressions:
exp -> lp exp rp | exp op exp | number
op -> plus | minus | times
The symbols, lp, rp, plus, minus and times refer to the lexemes (, ), +, - and *
respectively and the symbol number refers to any non-negative integer
Provide a declaration for a Java class that could be used to store parse trees for this
grammar. The methods of the class do not have to be declared.
我理解语法是什么，例如我可以使用加号，减号或次数作为运算符，我可以使用类似（5）的东西，即lp exp rp。把它转换成一个类丢失，这是我迷路的地方。我已经阅读了教学内容，这是非常轻松的。任何指导都会受到赞赏。