氧气穿过无数肺泡的薄壁进入毛细血管中，随后经肺静脉带到心脏。

Oxygen passes through the incredibly thin walls of the alveoli into the capillaries and is then carried back to the heart via the pulmonary veins.

youdao

氧气穿过无数肺泡的薄壁进入毛细血管中，随后经肺静脉带到心脏。

Oxygen passes through the incredibly thin walls of the alveoli into the capillaries and is then carried back to the heart via the pulmonary veins.

youdao