骨的外层为质密的骨皮质，包围着海绵状骨松质中心区（不算骨髓腔）。

An external layer of compact Bone surrounds a central area of spongy Bone, except at the marrow cavity.

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如果质密物体的质量，大于，太阳质量的三倍，毫无疑问我们就认为，它是个黑洞，从那时起，很多黑洞。

And clearly, if the mass of that compact object is way larger than three solar masses, then there is no doubt in our minds that this is a black hole.

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多彩的神经元密质部分位于前景，背景上的明暗模式表明了结构上的差别。

Behind the colorful somata in the foreground, a pattern of light and dark in the background suggests anatomical distinctions.

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They sit deep within our brain and are enclosed by a dense bone.

这种细胞由骨密质包裹着,位于大脑的内部。

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