That could be because the collision that made the moon in the first place was so hot that volatile elements like hydrogen, a key component of H2O, largely burned away.
这可能是因为月球形成过程中，撞击产生的热能使挥发性氢元素——水的重要组成成分——大量流失。
2
This work focus on the calculation of the cross-section of the electron-hydrogen like Uranium collision. The interference effect of DR and RR was investigated near the resonant energy.
本工作计算了电子与类氢的铀离子碰撞截面随能量的变化，研究了在共振能量附近，DR和RR过程的干涉。
3
But the collision probability of the spray particle against the cylinder wall will increase when the hydrogen concentration in the air exceeds a certain limit.