But 20th century medicine did little to increase the natural life-span of healthy humans.

然而，20世纪的医学对健康人的自然生命周期的增长几乎无能为力。

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Some are so slow growing they never would have caused medical problems in the person's natural life span.

一些肿瘤长的那么慢，它们从不会在一个人的自然生存期内导致问题。

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Such of words, ignore to die in what circumstance, the eyes power of god of also just it original natural life span.

这样的话，不管死于什么情况，死神眼看到的也只是其原本的自然寿命。

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Scientists have long speculated that the key to a person's "natural" life span lies in so-called diseases of aging, those that emerge only as the body begins to wear out.

WSJ: A Gene Gives a Hint Of How Long a Person Might Hope to Live