For some the sound could make sleep harder, but for others, the steady beat of the ticking, or the quiet hum of an electric motor in a fan can be very peaceful.

有些东西发出的声音令你很难入睡，但有些东西是固定行走或敲打的，风扇有规律的转动的声音听起来很和平。

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An induction motor, by contrast, can be cooled passively-and thereby dispense with the hefty radiator, cooling fan, water pump and associated plumbing.

相反地，诱导式发动机可以自冷却，这样就省去了笨重的散热片、冷却风扇、水泵和与此相关的铅用品制造。

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While one of the crew was using the Russian-made toilet last week, the toilet motor fan stopped working after “it made a loud noise”, according to NASA.

据介绍，上周一名宇航员上厕所时，“马桶突然发出一声很大的声响”，厕所的风扇就不转了。

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