They also have 30 percent more feathers in the winter and can fluff them up, trapping a layer of warm air.

它们的羽毛在冬季也要增加30%，它们把羽毛蓬松开，来保留住一层温暖的空气。

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This is covered by an upper layer of warm air that ACTS like a lid. It prevents the polluted cooler air from rising.

这层冷空气就阻挡了这些被污染的冷空气，使之不能上升的高空中。

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Whereas dolphins and whales rely on thick blubber to help keep warm in cold water, fur seals and sea otters depend on dense fur to trap a layer of air against their bodies.

在寒冷的水域中，海豚和鲸鱼依靠它们厚厚的脂肪进行保暖，而海狗和海獭则依赖于它们那稠密的皮毛来留住空气层。

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