void setup() {
  // 南北向控制:
  pinMode(3, OUTPUT);//绿
  pinMode(6, OUTPUT);//黄
  pinMode(9, OUTPUT);//红
  //东西向控制:
  pinMode(4, OUTPUT);//绿
  pinMode(7, OUTPUT);//黄
  pinMode(10, OUTPUT);//红
}

void loop() {
  // put your main code here, to run repeatedly:
  //南北向:
  digitalWrite(3, HIGH);//绿灯亮
  digitalWrite(6, LOW);
  digitalWrite(9, LOW);
  //东西向:
  digitalWrite(4, LOW);
  digitalWrite(7, LOW);
  digitalWrite(10, LOW);//红灯亮

  delay(5000);

  //南北向:
  digitalWrite(3, LOW);
  digitalWrite(9, LOW);
  for(int i=0;i<3;i++){//3秒黄灯闪烁，东西向保持红灯
      digitalWrite(6, HIGH);
      delay(500);
      digitalWrite(6, LOW);
      delay(500);
  }

  //南北向：
    digitalWrite(3, LOW);
    digitalWrite(6, LOW);
    digitalWrite(9, HIGH);//红灯亮
  //东西向：
    digitalWrite(4, HIGH);//绿灯亮
    digitalWrite(7, LOW);
    digitalWrite(10, LOW);

    delay(5000);

    //南北向保持红灯，东西向黄灯闪烁3秒
  digitalWrite(4, LOW);
  digitalWrite(10, LOW);
  for(int i=0;i<3;i++){
    digitalWrite(7, HIGH);
    delay(500);
    digitalWrite(7, LOW);
    delay(500);
  }

}