The lowdensity of the gas hampered many attempts to detect it in the past.
过去许多探测低密度气体的努力都受到了阻碍。
2
Scientists predicted that the gas would have a high temperature and so it would primarily emit low-energy X-rays. But its very low density made observation difficult.
科学家们预言气体温度可能很高于是会主要发射出低能的X射线。但是其过低的密度给观测带来困难。
3
Membrane separation technology is widely adopted in the gas separation application due to its special separation efficiency, low weight and high pack density.