Knowledge has to be improved, challenged and increased constantly or it vanishes.

知识需要提高和挑战才能不断增长，否则，它将会消亡。

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There are gaps, of course, and long ones, where it vanishes from view, temporarily lost or hidden; but always it resurfaces.

当然中间会有中断，很长时间的中断，它会从人们的视野里消失，暂时丢失或者隐藏起来，但总会重新出现。

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The second part of the system captures heat wasted during the first part, which usually sneaks up the chimney or otherwise vanishes unnoticed, and uses it to provide space heating or hot water.

FORBES: Big Apple Gambles on Clean Heat and Power