straight-line knurls

例句：

1. 1. He used a ruler to measure the length of the wall.
   他用直尺测量了墙的长度。
2. 2. The engineer drew a straight line on the map to indicate the route.
   工程师在地图上画了一条直线来指示路线。
3. 3. The carpenter used a ruler to make sure the cuts were accurate.
   木匠用直尺确保切割准确无误。