一个很好玩的游戏。 程序自动生成一个图片表达式，根据此表达式的内容，算出结果。（可根据此原理开发验证码） （本程序需要php的gd库支持才能运行） -A very fun game. The program automatically generates a picture expression, according to the contents of this expression, calculate the results. (According to the principle of the development of verification code) (This procedure requires PHP gd library support to run)