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。
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。
"One question not addressed is whether smog stabilizes bacteria in a way that normal air doesnot," he added.
“有一个疑问没有解决，那就是雾霾是否在某种程度上以一种普通空气无法实现的方式令细菌保持了稳定，”他接着写道。
It is a novel approach to full utilization of heat energy during heat treatment, with 30% increased heat efficiency compared to normal air condensers whose exhaust is directly put to atmosphere.
它开辟了一条热处理过程热能充分利用的新途径，比通常尾气直接排入大气的空气冷却器提高热效率30%以上。
DMC series Pulse Jet Bag Filter is the rectangular Dust Collector which has simple construction and can be use in a normal air volume range.
dmc系列脉冲袋式除尘器是一种结构简单，风量应用范围中等的矩形除尘器，被广泛应用于操作压力要求不高的各种条件下。
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。
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。
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