叱咤考场之阅读理解篇(下)

摘要：

C
People in developed countries are living longer.In 2005,the average lifespan of Americans was 77.6 years,compared with 54 years in 1920 and just 34 years in 1780.By 2050 it is estimated that the average lifespan will extend to around 85.By then,people over 60 will take up 26 per cent of the total population in developed countries.

机标关键词：考场、per cent

分类号：U47;TP3

在线出版日期：2016-12-20（万方平台首次上网日期，不代表论文的发表时间）

页数：共3页

页码：52-54