hydrogen

水分子由两个氢原子和一个氧原子组成。

A water molecule consists of two ___hydrogen atoms and one oxygen atom.

这家工厂使用氢作为清洁能源来发电。

This factory uses ___hydrogen as a clean energy source to generate electricity.

科学家分析氢和镭这两种元素。

The scientists analyse two elements: ___hydrogen and radium.