Any free moving liquid in outer space will form itself into a sphere, because of its surface tension.

在外太空，任何液体都会形成球体，因为表面张力。

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Because the Moon has no atmosphere, its surface is not subject to erosion, so it retains the marks of its early history.

由于月球没有大气层，它的表面不会受到侵蚀，所以它保留了早期历史的痕迹。

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The hyperbolic surface, which has so-called negative curvature because its surface curves up and down at the same time, like a saddle, just might represent the shape of the universe.

双曲表面，即通常所称的负曲率，因为它的表面曲线同时有的向上和有的向下，像一个马鞍，也许这样就可以代表宇宙的形状。

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There are certain scenarios, says Dr Lagace, where you might want to use a material because of its surface properties, but you might not want that property all the way through the material.

ECONOMIST: MONITOR

The moon is of great interest because of hints that it may have a huge ocean of water beneath its surface.

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