American forests are being devastated by foreign pests—and forests full of dead trees are prone to catastrophic fires. A fire in Washington State, above.

美洲的森林被外来害虫毁坏---满是死树的森林容易招致惨重的大火。

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The evergreen forests of the Amazon and Congo basins, for example, are generally fire-free because the closed canopy maintains a level of humidity that inhibits burning.

例如，亚马逊和刚果盆地的乔木通常是防火的，因为它们遮天的树冠保持了一定的湿度，抑制了燃烧。

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Fire was used initially for warmth, light, and cooking; later it was used in fire drives in hunting and warfare, and for clearing forests of underbrush to facilitate hunting.

火的最早用途是取暖、烹调，后来才用于狩猎和作战，以及为了捕猎而清除下层丛林。

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Fire was used initially for warmth, light, and cooking; later it was used in fire drives in hunting and warfare, and for clearing forests of underbrush to facilitate hunting.

火的最早用途是取暖、烹调，后来才用于狩猎和作战，以及为了捕猎而清除下层丛林。

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