position clock

例句：

1. 1.The position clock on the wall shows that it's time for lunch.
   墙上的钟表显示该吃午饭了。
2. 2.He set up a position clock to track his progress in the field.
   他设置了一台位置时钟来跟踪他在田野里的进展。
3. 3.The position clock was an essential tool for measuring distances accurately.
   位置时钟是准确测量距离的重要工具。