automatic pirn changing mechanism

例句：

1. 1. The car has an automatic pirn changing mechanism that allows you to easily change gears without having to manually shift the clutch.
   这辆车有一个自动换挡机制，可以让你轻松地换挡，而不必手动踩离合。
2. 2. The new model of the car has a more sophisticated automatic pirn changing mechanism that improves fuel efficiency and reduces emissions.
   这款新车的自动换挡机制更为先进，提高了燃油效率并减少了排放。
3. 3. The engineers worked tirelessly to develop a new automatic pirn changing mechanism that could handle heavy loads with ease.
   工程师们不懈努力，开发了一种新的自动换挡机制，可以轻松应对重载任务。