四位抢答器

代码说明：

  四路抢答器。首先通过主持人按下抢答按键代表抢答开始， 其他四人进行按键抢答，一个抢到后，其他人不可以进行操作。(Four way responder.First of all, through the moderator press answer button, on behalf of answer start, Other four people to answer the key, after a grab, other people can not operate.)