0--59不断运行的秒表，要求每1秒到，数码管的秒数 增一，加到59时，再过一秒，又回到零，如此循环。-0- 59 continue to run the stopwatch, to require every 1 second that the number of seconds by a digital tube, when added to 59, another second, then back to zero, and so on.