Hydrogen (H) is the most common element in the universe, and water (H2O) is the most common compound, meaning that you can get hydrogen just by breaking up water.
氫（Ｈ）是宇宙中最多的元素，而水（H2O）是宇宙中最多的化合物，只要分解水即可獲得氫，可以說是取之不盡。