Air circulating through these sacs transfers oxygen into the bloodstream that picks up the blood's carbon dioxide waste.

对于哺乳动物，每次吸气都将富氧空气带进肺中被称为肺泡的“死胡同”。 这些在肺泡中循环的空气通过与肺毛细血管的血液进行气体交换，输进氧气并带走血液中的二氧化碳。

youdao

An electric fan keeps the air circulating.

电风扇使空气流通。

youdao

It is prevented by controlling the relative humidity of the circulating air and the temperature of the air.

控制循环空气的相对湿度和空气的温度可防止表面硬化的出现。

youdao

There were crying babies, screaming customers, non-circulating air and way too much stress.

FORBES: Apple Stores Lose Appeal, Need Shot Of Starbucks

Once emitted, it persists in the environment for a long time - circulating through air, water, soil and living organisms - and can be dispersed over vast distances.

BBC: Nations agree on legally binding mercury rules

The wind gains strength from the thermal energy of the ocean, eventually condensing vapors and circulating air fast enough to form high-speed wind and heavy rain.

CNN: graphic