The number of spots on its surface has waxed and waned in cycles that last, on average, 11 years.

太阳表面的黑子数在其一般延续11年的活动周期内增增减减。

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Pluto, now classed as a dwarf planet, is so small and so distant that its surface has been a mystery to astronomers.

现在归类于矮行星的冥王星是那么小，那么远，对天文学家来说，其表面一直是个谜。

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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.

双曲曲面，即通常所称的负曲率，因为它的表面同时向上和向下弯曲，就像一个马鞍。

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Scientists have long believed that Earth's satellite lacks the ability to hold water near its surface because it has no atmosphere.

VOA: special.2009.09.30

These countless words, listed with their many pronunciations and the regions where they were found, must persuade anyone like Johnson who imagines he knows his own language just how little of its surface he has in fact begun to scratch.

ECONOMIST: Johnson: The words we have lost | The

The HPS has issued its standard, Surface and Volume Radioactivity Standards for Unconditional Clearance.

FORBES: Does The DoD Want To Kill Us All With Radioactive Nuclear Scrap Metal? No, No Not Really

Microsoft has started shipping its first Surface tablet computers ahead of their official launch on Friday.

BBC: Surface tablets start shipping ahead of Windows 8 launch