1. Water may be resolved into oxygen and hydrogen.
    水可以分解成氧和氢。

2. The Earth was formed about five billion years ago from a rotating, circular cloud of dust and gases such as hydrogen and nitrogen.
    地球的形成约在50亿年前，起源于一团循环旋转的尘埃和诸如氢、氧之类的气体。

3. Hydrogen and oxygen are gases.
    氢和氧都是气体.

4. Hydrogen is the lightest element.
    氢是最轻的元素。

5. And the outer planets have temperatures near absolute zero and hydrogen-dominated atmospheres.
    除此之外，太阳系的其他行星的温度都接近绝对零度，并围绕着以氢气为主的大气层。

6. Analyse water into oxygen and hydrogen.
    把水分解成氧和氢。

7. A molecule of water consists of two atoms of hydrogen and one atom of oxygen.
    水分子含有两个氢原子和一个氧原子.

8. It is the natural frequency of emission of the hydrogen atoms in space .
    这是空间氢原子“释放”的自然频率.

9. It is the natural frequency of emission of the hydrogen atoms in space and was discovered by us in 1951;
    这个频率是空间氢原子释放的自然频率，是在1951年被人类发现的。