And the vagaries of quantum physics mean that "too many" and "too few" sometimes overlap, and there is thus no stable isotope (or variant, with fewer or more neutrons) of a particular element.

难以捉摸的量子力学表明，中子“太多”和“太少”有时会重叠出现，因而一些特定的元素没有稳定的同位素(或称变体，核内中子数不同)。

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And as an added incentive for you to pay attention, I'm going to warn you that this particular simulation will appear in the final or a variant of it.

作为提高你们注意力的激励，我要警告你们,这个特殊的仿真程,或者它的变种会再期末考试出现。

麻省理工公开课 - 计算机科学及编程导论课程节选

Somewhere along the line, H3N2 and H1N1 viruses were present in a mammal at the same time, and the "matrix-gene" (or m-gene) from the H1N1 pandemic virus was picked up by the H3N2 swine flu, creating a new or variant version of H3N2.

CNN: CDC: Cases of new swine flu strain rising

Somewhere along the line, H3N2 and H1N1 viruses were present in a mammal at the same time and the "matrix-gene" (or m-gene) from the H1N1 pandemic virus was picked up by the H3N2 swine flu, thus creating a new or variant version of H3N2.

CNN: CDC: Increase seen in new swine flu strain

So, in that regard, GM is doing well to not only widen its product range but also offer customers the option of petrol or diesel variant.

FORBES: GM Stock Good For Drive To $25 With Room To Improve In India