四人抢答器，　有4组抢答，系统开始后进入抢答状态，抢答开始后20秒倒计时，20秒倒计时后无人抢答显示超时，发出报警信号；当有一路抢答按键按下，该路抢答信号将其余各路抢答信号封锁，同时铃声响起，显示该路抢答台号；一轮结束后按复位键将所有状态复位。-Four Responder, Responder has four groups, the system begins to enter the answer in the state, began to answer in 20 seconds af