Insurers could not deny coverage to people who already have a condition, or cancel coverage if people get sick.
VOA: special.2009.09.12
The reason is because we already have a full valence shell for our hydrogen, it doesn't want any more electrons.
原因是因为我们的氢,已经有一个排满的价壳层了,它不再需要多余的电子了。
So, you already have a hint that methyl groups are never in the middle, they always have to be on the outside.
那么,你已经得到了一个提示,那就是甲基永远都不可能在中间,它们总是在外侧。
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