看论坛上有个要钱的关于数学运算表达式的东西，之前写过一个关于数学表达式的单元，现免费发给大家了，当然因为只是临时用才写的，有些粗糙，请原谅。-Have a look forum money on things mathematical expressions, written before the mathematical expression on the cell, is distributed free to the U.S., of course, because it is only