所设计的抢答器允许四人参加。在出题后，红色发光二极管点亮，同时显示器显示秒信号，A、B、C、D四人按动按钮以决定先后次序，计时到60s之后即依次显示四个人的名次，若超过60s未按按钮者不计名次。在红灯亮前按下按钮者也不计名次。-The Responder is designed to allow four people to participate. In a later question, the red light-emitting diodes lit at the same time d