设计了一个数字钟，可以完成00:00:00到23:59:59的计时功能，并在控制电路的作用下具有保持、清零、快速校时、快速校分、整点报时等功能。-Design a digital clock, timing functions can be completed from 00:00:00 to 23:59:59, and has to maintain the role of the control circuit is cleared quickly School, rapid correct