presence have made it a recognizable symbol of American enterprise worldwide. 现象：按下k1,k2,rst,分别有led灯对应点亮。 测试：可以测试3个用户按钮是否正常。 McDonald's innovation in drive-through service fundamentally changed how consumers access fast food. For each socket unit, a matching service unit must exist, describing the service to start during booting and the