齿轮连上

例句：

1. 1. The car's engine is connected to the gearbox with a belt.
   这辆车的引擎通过皮带与齿轮箱相连。
2. 2. The old man was trying to shift the heavy gear with his hands.
   那个老人正试图用手来换挡沉重的齿轮。
3. 3. The engineer adjusted the gear ratio for better performance.
   工程师调整了齿轮比以获得更好的性能。