说明：  交通灯的显示有很多方式，如十字路口、丁字路口等，而对于同一个路口又有很多不同的显示要求，比如十字路口，车子如果只要东西和南北方向通行就很简单，而如果车子可以左右转弯的通行就比较复杂，本实验仅针对最简单的南北和东西直行的情况。
(Traffic lights show there are many ways, such as intersections, T-junction, etc., and for the same intersection there are a lot of different display requirements, such as crossroads, if the car as long as the north-south direction and pass something very simple, but if the car can be left and right turning traffic is more complex, the present experiment only for the simplest of north-south and east-west straight.)