The first bubbles to escape from the liquid are a mixture of air and hydrogen.
从该液体中最先逸出的气泡是空气和氢的混合物。
《新英汉大辞典》
2
Hydrogen is lighter than air, but compressing it, storing it in tanks and adding all the necessary equipment starts to tip the scales towards heavy again.
氢气比空气轻，但是将它经压缩存储在燃料箱中并添加所有必需设备后飞机又变重了。
3
Fuel cells combine hydrogen and air to produce electricity by running them through a chemical catalyst. The only byproducts are heat and water.