名词
中文翻译：双档位齿轮
同义词：
['double gear', 'double-speed gear例句：1. The car has a double back gear that allows for easy acceleration.（这辆车有双档位齿轮，可以轻松加速。）2. The old bicycle had a double back gear that was difficult to shift.（旧自行车有一个双档位齿轮，很难换挡。）']
例句：
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1. The car has a double back gear that allows for easy acceleration.
这辆车有双档位齿轮，可以轻松加速。
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2. The old bicycle had a double back gear that was difficult to shift.
旧自行车有一个双档位齿轮，很难换挡。
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3.The new car comes with an automatic double back gear system.
新款汽车配备了自动双档位齿轮系统。