Experimentally, though, that's not such an easy situation to arrange.

但是保持熵恒定在实验上很难实现，当然保持温度。

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So it's hard to realize that in the terrestrial situation.

这在现实世界很难实现

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Of course,that's a big if.

当然这个，如果，是很难实现的。

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Oftentimes, inventions that seem, in the abstract, to be good ideas may be impossible because something that you have to do to make it actually come into practice is too expensive and so it's not economic to produce the invention.

通常在理论上,创新固然不错,但却很难实现,因为把创意变成现实,花费会相当的昂贵,实现这样的创意非常不合算

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