signal splice

例句：

1. 1. The policeman used his whistle to signal the driver to stop.
   警察用哨子示意司机停车。
2. 2. The traffic lights are designed to signal when to stop and go.
   交通信号灯设计用来指示何时停车和行驶。
3. 3. The GPS system uses signals from satellites to guide a vehicle's navigation.
   全球定位系统使用来自卫星的信号来指导车辆的导航。