The average life span of humans continues to lengthen, and some scientists have begun to ponder whether this trend will continue indefinitely.

随着物质生活的不断提高，人类的平均寿命有不断变长的趋势。一些科学家们也开始仔细思考这个趋势是否会一直持续下去帮助人类达到永生。

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Compare this with an average life span of 52 in 1960, or of about 30 in 1900.

把这个数字与1960年的平均寿命52岁相比，又或者与1900年的人均30岁寿命相比。

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The tiny European nation of San Marino boasts the longest average life span for men, with 81 years.

欧洲小国圣马力诺则成为男性平均寿命最长的国家，为81岁。

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There is a high mortality rate -- with an average life span of only 47 -- minimal infrastructure and limited tools for economic development.

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