在二十世纪以前，没有人经历过人口总数成倍的增长，但是如今有活着的人看到了三倍的人口增长。

Before the 20th century, no human had lived through adoubling of the human population, but there are people alive today who haveseen it triple.

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当我们经历过人生就会发现，没有人能够风平浪静地度过一生。

As we go through life, we'll see no one can live a smooth life.

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