求翻译：既能体现公平又能促进效率、既能提高社保水平又能不增加政府负担的社会保障制度对一个国家来说至关重要。20世纪30年代以来，美国社会保障制度逐步建立并不断发展变化，随着70年代后期的人口老龄化和经济全球化的影响，欧美国家面临着福利的需求和供给的矛盾，传统的社会保障模式亟待改变。近年来，奥巴马以医改为突破口，力图完善美国社会保障制度。然而受金融危机后遗症的制约，面对社会保障水平提高与削减政府开支这对矛盾，美国社会保障制度发展前景不容乐观。是什么意思？

, Which reflects the fair also promote efficiency, both to improve the social security level can not increase the government's burden on the social security system is essential for a country. Since the 1930s, the U.S. social security system gradually established and constantly evolving, with the lat

It is also fair to promote efficiency, as well as to be able to improve the social security level added to increase the burden on the government social security system in a country that is crucial. Since 1930s 20th century, the United States social security system step by step to establish and conti

Also also both can manifest fairly and can promote the efficiency, to be able to enhance society guarantees the level to be able not to increase the government burden the social security systems to a country very important.Since the 20th century 30's, the US social security systems have established

Both fair and promote efficiency, while raising the level of social security will also not increase the burden on the Government's social security system is crucial for a country. In the 1930 of the 20th century, the United States social security system established and evolving gradually, as populat

正在翻译，请等待...