广播电视英语短句 第 238 课：痴呆的主要原因-4

But their numbers are growing quickly. 但是老年人的数量在飞速增加。

They are expected to reach twenty percent of the total population by the middle of the century. 他们预计到本世纪中期老年人将达到总人口的 20% 。

The study appeared in the Lancet medical journal which published a special issue （特刊） on disability. 研究结果在 Lancet 医学周刊公布的伤残特刊上发表。

A separate study of eighteen low and middle income countries dealt with children. 一个单独研究针对 18 个中低收入国家的儿童。