We all need vitamin d, which is a nutrient that can be obtained by catching some rays.

我们都需要维生素d，它可以通过光照获取。

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Here the benefits of dark skin are outweighed by the need for bone-strengthening vitamin d, produced through exposure to UV rays.

这个地区人们通过照射紫外线来获取骨骼生长所需要的维他命d，所以深肤色的优势已凸显不出。

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The irony is that the same UV rays that trigger vitamin D production in your body also produce chemical changes in the skin's DNA.

具有讽刺意味的是，紫外线在你身体里产生维他命D时候同样也会改变你皮肤的DNA结构。

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C.D.C.officials say U-V rays can damage your skin in as little as fifteen minutes.

VOA: special.2010.07.06

Until the 1980s radiation oncologists could only crudely estimate where to aim based on the position of nearby bones in 2-D X rays.

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Games aside, the system can play 3-D Blu-rays and movie downloads.

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Exposure to the sun's rays normally generates Vitamin D in the skin, but applying sun block stops that process.

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