1·The lumen of the acinus is small and narrow but that of the alveolus is large and distended.
单腺泡腔小而狭窄，但肺泡的腔却大而膨满。
2·Pulmonary alveolus: Any of the 300 million or so small air Spaces in the lungs where carbon dioxide leaves the blood and oxygen enters it.
肺泡：肺内的约3亿个小气囊，于此，二氧化碳从血中排出，氧气进入血液。