In some parts of the world, cyclists have been powering safety lights for years with devices called bicycle dynamos, which use a generator to create alternating current with every turn of the wheels.

在世界的一些地方，骑自行车的人已经通过叫自行车发电机的装置产生了多年的安全电能。当自行车车轮转动的时候一个装在上面的发电机就会产生交流电。

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