说明：  吉大短学期CPLD实习程序 设计一个 4 路抢答器，当按下抢答键开始抢答，设置 4 个按键作为 4 路抢答开关，4 个LED 作为抢答显示，一旦抢答成功，蜂鸣器发声，与抢答开关对应的 LED 亮
(Chittagong short term internship program CPLD design a 4-way Responder, Responder to start when you press the answer in, set the four keys as the answer in 4-way switch, 4 LED display as a Responder, if answer in successfully, the buzzer sound, and answer in the corresponding LED light switch)