青蛙是两栖动物，幼体在水中呼吸，成年后变为用肺呼吸。

Frogs are amphibians that start as water-breathing tadpoles but become ___air-breathing adults.

喷气式飞机使用的是需要大气中氧气的发动机。

Jet planes use ___air-breathing engines that require atmospheric oxygen.