当然，实际上你必须有电源供应，用以维持磁场。

Of course, I mean, you actually have to take some power supply to maintain the magnetic fields.

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项目在计算机切换到一个可维持十分钟的紧急电源后被挽救了。

The project was saved when the computer switched to an emergency 10-minute back-up power source.

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然而研制这种微小、轻型的飞行器是很困难的，因为必须要有如板载电池这样的电源供电才能维持它的飞行。

But building a tiny, lightweight flying robot is tough when you need a power supply — like an onboard battery — to keep the MAV flying.

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