根据文章第段一People worldwide are living longer.(世界各地的人们寿命越来越长)和By 2050,there will be almost this many (120 million)living in China alone,and 434 million people in this age group worldwide.(到2050年,仅中国就将有近1.2亿人生活在这个年龄段,全球将有4.34亿...