the mass of 与 a mass of 有啥区别?

the mass of 与 a mass of 有啥区别? mass的用法the mass of 和 a mass of 有什么区别？ The elements of a compound occur in a fixed mass ratio.请问fixed mass ratio THE MASS the mass mass a mass a mass of =masses of吗? 英文翻译as the mass of air rises a mass of 的近义词和词性 a mass of是什么意思及用法 The club women gathered____clothes for people in the tsunami-hit countriesA a mass of B mass of C a large amount of D amount of 为什么选A The atomic mass of copper is 63.55 amu.There are onlytwo isotopes of copper,63Cu with a mass of 62.93 amu and65Cu with a mass of 64.93 amu.What is the percentageabundance of each of these two isotopes? a mass of与a mount of与many of的区别 ___rock had fallen from the cliff and now blocked the road.A.Masses of B.A great mass of C.A much mass D.A mass of 选哪个,为什么其他的不行.要区别!= =谢谢了 The mass of 0.02mol of a substance is 0.88g1.what is the molar mass of this substance?2.what is its chemical formula? the mass 什么意思? 翻译“the mass-era ”