[简答题]21世纪是人口老龄化的时代(aging population)。中国已于1999年进入老龄社会，是较早进入老龄社会的发展中国家之一。中国是世界上老年人口最多的国家，中国的人口老龄化不仅是中国自身的问题，而且关系到全球人口老龄化的进程，备受世界关注。截至2011年底，中国60岁及以上老年人口达1.85亿，预计到“十二五”期末，全国老年人口将增加到4300多万，达到2.21亿。人口老龄化必将带来一些新的矛盾和压力，对经济和社会的发展提出新的挑战。

参考答案: The BAst century is the era of aging population. China has entered the aging society since AIII, and becomes one of the developing countries with aging society at an early time. China is a country with largest elderly population in the world. The aging population is not only China’s own problems, but also affects the aging process of global population, thus attracting worldwide attention. As of the end of B0AA, the scale of China’s elderly population above the age of F0 is up to AHE million, with an estimated number of more than DC million to be added by the end of the "Twelfth Five-Year Plan" period, namely amounting up to BBA million in total. The aging population is surely to cause some new contradictions and pressures, and bring new challenges on economic and social development.