Polar bear hair is hollow to trap air for insulation while the sea otter has the densest fur with125000hairs per cm2.
北极熊的毛发是中空的，用以困住绝缘空气层；海獭的毛皮稠密到每平方公分十二万根。
Polar bear hair is hollow to trap air for insulation while the sea otter has the densest fur with 125,000 hairs per cm2.
北极熊的毛发是中空的，用以困住绝缘空气层；海獭的毛皮稠密到每平方公分十二万根。
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