signal halyard

例句：

1. 1. The policeman signaled the driver to stop.
   警察向司机示意停车。
2. 2. The ship's radio was used to signal for help.
   船的无线电被用来发出求救信号。
3. 3. The pilot signaled for a landing at the airport.
   飞行员在机场发出着陆信号。