利用数码管实现交通灯 东西向绿灯亮若干秒后，黄灯闪烁，闪烁5次后红灯亮红灯亮后，南北向由红灯变为绿灯，若干秒后南北向黄灯闪烁闪烁5次后亮红灯，东西向绿灯亮，如此重复-East-west green light for several seconds after the flashing yellow light, red light flashes 5 times after red light, red light into green light from the north-south