理论上，你需要核心里的熔化铁来产生它，但是水星很小，它的核心凝固还要很久。

In theory, you need molten iron in the core to generate one, but Mercury is so small, its core should have long since solidified.

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然后加入更多的这种粉状材料，熔化后再凝固，层层堆积，直到最后形成要制造的物品。

Then more powder is added, melting and solidifying to add layer upon layer until the object is fully formed.

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进一步的理论说明，一旦熔化的碎片合并到月球上，月球的地壳凝固时间超过了几亿年。

Once the molten debris coalesced into the moon, the theory goes, its crust solidified over several hundred million years.

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