说明：  程序扫描键盘，当B键按下时，在屏幕上显示0～9循环计数；S键按下时停止计数；再按B键继续计数过程。E键按下时退出程序。 3、用DEBUG调试程序预置数据和查看程序运行结果，以验证程序正确性
(The program scans the keyboard displayed on the screen, when the B button is pressed, 0 to 9 loop count stops counting when the S key is pressed then press the B key to continue the counting process. E key is pressed to exit the program. DEBUG debugger preset data and view the results of the program to run, in order to verify the correctness of the program)