在元素中,氦是非常特别的。它的原子量仅次于氢,是第二个最轻的元素。在宇宙间,它的丰度也仅次于氢,是第二个数量最多的元素;一般恒星的能源都是来自氢聚变为氦。但是,在地球上它却是一种稀有气体,在大气中的含量仅占0.0005％强。只有某些油气田产出的天然气中氦的含量多些,可以占7.6％。然而最叫人惊奇的还是 Among the elements, helium is very special. It is second only to hydrogen, the second lightest element. In the universe, its abundance is second only to hydrogen, which is the second most abundant element; the energy of most stars is from hydrogen to helium. However, it is a rare gas on Earth, its content in the atmosphere is only 0.0005% strong. Only natural gas from some fields yields more helium, accounting for 7.6% of the total. However, the most surprising thing is