设计一个十字路口的交通灯控制电路，要求东西方向车道和南北方向车道两条交叉道路上的车辆交替运行，每次通行时间都设为45秒-Design of a crossroads of traffic lights control circuit, require lane east-west direction and cross the two-lane north-south direction on the road to the turn of the vehicle running time of