radio signal

例句：

1. 1. The police received a distress signal from the ship.
   警方收到了来自船只的求救信号。
2. 2. The scientist used a radio signal to communicate with his team.
   科学家使用无线电信号与他的团队进行通信。
3. 3. The satellite sent a radio signal to Earth.
   卫星向地球发送了无线电信号。