As Dr Hazen pointed out, carbon is the fourth-most-abundant element in the universe, after hydrogen, helium and oxygen. In the Earth, though less common than that, it is reckoned to make up between 0.07% and 3.2% of the planet. But the uncertainty of this range is itself a comment on how little carbon's role in the Earth's overall physics and chemistry is understood. Also uncertain is how much interchange there is between the carbon in the Earth's mantle and core, and the more familiar stuff in the crust, atmosphere and oceans.
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As Dr Hazen pointed out, carbon is the fourth-most-abundant element in the universe, after hydrogen, helium and oxygen.
就像Hazen博士指出的那样，碳是宇宙中含量排第四的元素，仅落后于氢，氮和氧。
Results it shows that the control of oxygen concentration after unchaining coupling is a vital technology in assistant breathing equipment cycled with mixed gases of helium and oxygen.
研究结果表明：氧浓度解耦控制技术是循环式氦氧混合气辅助呼吸装置设计中的一项关键技术。
Cold plasma, a combination of oxygen and helium gas concentrated into a lightening-like beam, has previously been used by medics to clean bacteria off wounds.
冷等离子，是由氧气和氦气混合集中成的光束，先前主要在医疗上用来清除伤口的细菌。
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