Comets consist of "dirty ice", rather than solid rock, and so contain little iridium.

彗星是由“脏冰”所组成，而不是像小型那样由固体岩石组成，所以只含有少量的铱。

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Ganymede, the largest moon in the solar system, has a dirty ice surface cut by fractures and peppered by impact craters.

这颗太阳系中最大的卫星，表面冰盖布满断层的切口和火山灰的粉末。

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Since plants had not yet evolved 700 million years ago, the dirty ice could have been the only dark spots on Earth's surface to absorb the sun's rays.

7亿年前地球上还没有植物，浑浊的冰（泥土和冰的混合物）可能是地球表面唯一能够吸收阳光的黑色物质。

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We have a pretty good idea that they're made of dirty ice, but beyond that, we don't really know the details of what they're made of.

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When the ice sheets were thick and advancing, more pebbles, stones, and dirty sediment would have been carried into the core by the moving ice.

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