1、 The permafrost contains immense amounts of frozen organic matter that have been accumulating for millennia.
永久冻土层经过千万年的累积形成,其中包含了巨量的冻僵的有机物.
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2、 Through subsequent millennia It'spread to other regions and increased in sophistication.
接下来的几千年,农业扩张到其他地区,技术也逐渐提升.
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