line counter

例句：

1. 1. The line counter is used to measure the length of the rope.
   线计数器用于测量绳子的长度。
2. 2. The engineer used a line counter to check the accuracy of the measurements.
   工程师使用线计数器来检查测量的准确性。
3. 3. The line counter was used to count the number of people in the room.
   线计数器被用来数房间里的人数。