We are family: Scientists suspect that a large DNA-based virus took up residence inside a bacterial cell more than a billion years ago to create the first cell nucleus.

病毒跟我们是一家人：科学家认为，十多亿年前一个大的DNA病毒在细菌细胞内居住并形成了第一个细胞核。

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With the influx of people relocating to different parts of the country, and the passing of older ones, who were the nucleus of some families, many realize that family closeness is fading.

随着大家不断的搬居到其他地方，随着过去家庭核心成员老年人的去世，很多人意识到家人的亲近度在降低。

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Many people believe that the family is the nucleus of the community.

许多人认为家庭是社会的核心。

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With the nucleus of the family in shambles, the fabric of American society is unraveling one thread at a time.

CNN: Reduce poverty by promoting schools, families

And so, I just think that it was sort of the nucleus of the family to go back to, better than being isolated, perhaps, in a state that, maybe grudgingly, allowed interracial marriage.

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