shifting slide gear

例句：

1. 1.The car had a shifting gear that was difficult to use.
   这辆车有一个难以使用的换档装置。
2. 2. The mechanic changed the gear shifter on the car.
   机械师更换了汽车的换档装置。
3. 3.The old car had a worn out gear shifter, which needed to be replaced.
   旧车的一个磨损的换档装置需要更换。