Volunteers were told to think about yawning while they breathed either normal air, pure oxygen, or an air mixture with an above-normal level of carbon dioxide.

当志愿者在正常的空气中、纯氧的环境下，或者混有超过正常的二氧化碳含量的空气中呼吸时，他们被要求要想着打哈欠。

youdao

Volunteers were told to think about yawning, while they breathed either normal air, pure oxygen, or an air mixture with an above-normal level of carbon dioxide.

当志愿者在正常的空气中、纯氧的环境下，或者混有超过正常的二氧化碳含量的空气中呼吸时，他们被要求要想着打哈欠。

youdao

Normal air pressure is about 15 pounds per square inch.

正常的气压大约是每平方英寸15磅。

youdao

"These are the same kind of fine matter found in normal air pollution.

VOA: standard.2010.04.16

Allen Hershkowitz with the Natural Resources Defense Council, a private environmental group, says air quality around landfill sites must be carefully checked when oil-contaminated waste is added to normal household trash.

VOA: standard.2010.08.05

And the prospect of a return to normal air travel remains far from clear.

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For example, because normal air conditioning is inadequate for lunar conditions, we were required to use cold water to cool the interior of our suits.

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Package tourists were invited to wing their way in for two weeks at the grandest hotels for the price of half the normal air fare.

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