
给定以下文法 factor → digit | (expr ) term → term × factor | term / factor | factor expr
8.给定以下文法 factor → digit | (expr ) term → term × factor | term / factor | factor expr → expr + term | expr – term | termdigit → 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 (1)构建以下表达式的语法树 (a)1+2-3 (b)1+2×3/4 (2)添加(a)的语法树的属性值(term.t=…) (3)添加(a)的语义动作(print …)