Ornithischian dinosaurs like Triceratops and Stegosaurs lack these air sacs and as a result, most of them weren't very big.

三角龙和剑龙属于鸟臀目恐龙，缺少这些气囊，因此它们大多数的体型并不大。

The alveoli are tiny air sacs that look like tiny clumps of grapes, that are wrapped up in a net of capillaries.

肺泡是微小的气囊，看起来像小丛葡萄，包裹于毛细血管网中。

Initially, doctors had no way to alter the stretchability or squeeziness of their patients' air sacs.

最初，医生没有办法改变病人肺泡的拉伸性或挤压力度。

Walruses have an air sac under their throat, which helps them float vertically in the water and sleep.

海象的喉咙下面有一个气囊，帮助它们在水中垂直漂浮和睡觉。

They then lunge forward, or strut, to forcefully push the air in and  out, rapidly inflating and deflating the air sacs.

然后，它们向前冲刺或昂首阔步，用力将空气推入和推出，迅速使气囊膨胀和放气。