One possibility is that it has something to do with how our brains process information, she adds, but "we cannot be very certain about it."

她补充说，一种可能性是此阶段可能与我们大脑如何加工信息有关。 但是“我们对此不能十分确定。

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Kids who have certain bacterial infections can be very compulsive about touching their mouths, which helps the spread.

有些孩子感染某种细菌之后会强迫性的触碰他们的嘴，这有助于细菌传播。

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There may very well be a great shortage of labor of certain kinds, with no prospect of any shifting or adapting which will bring about an increased supply.

某些种类的劳动力很可能会大量短缺——我们对经过转移或适应而带来劳动力的增加实在不抱希望。

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