The modern atmosphere supports many forms of complex life that would not have been able to exist in Earth's first atmosphere because the oxygen level was too low.

现代大气层支持着许多复杂的生命形式，而这些生命在地球最初的大气层中是不可能存在的，因为当时的氧气含量太低。

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At the bottom of the ladder we squat in a narrow passage, while Anne-Marie Leparmentier, a geologist, measures the oxygen level.

在梯子的底部我们蹲着移入一条狭窄的通道，与我们同行还有一位叫安妮玛丽.丽帕米蒂尔的地质学者，她的工作是测量空气含氧量。

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With some hazardous materials, you can provide further protection by using inert gas to limit the oxygen level in the vacuum dryer.

随着一些有害材料，可以提供进一步的保障真空干燥机使用惰性气体中氧气含量的限制。

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Far below sea level, they contain some of the harshest environments on Earth, with no oxygen and no light.

VOA: special.2010.11.10

The respiratory system plays an important role in maintaining our internal environment at the proper level of oxygen, by bringing the right amount in.

呼吸系统的重要性在于,通过向体内输入适量的氧气,维持人体内环境中的氧平衡

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Next Roth lowered the oxygen level in their cage to 5% from 21%.

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As the oxygen level fell, though, something else rose: the level of urea.

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This involves shining a light into the brain to discern how much activity is there, and examining the corresponding oxygen level.

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