signal mast

例句：

1. 1. The signal mast is the tallest building in the city.
   信号塔是这座城市最高的建筑。
2. 2. The beacon on the mountain was used to guide ships during the fog.
   山上的灯塔在雾天用来引导船只。
3. 3. The antenna pointed towards the southwest, searching for a better signal.
   天线指向西南方向，寻找更好的信号。