提高听力同时，你还可以了解到美国历史上的一些重要事件。请感兴趣的你一听为快吧！
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hints：国家名大写
The United States has dramatically changed from its beginnings as 13 little-known colonies. Its population of 300 million people represents almost every national and ethnic group in the world. Progress continues in economics, technology, culture and society. Americans live in an interdependent, interconnected world. The United States still is connected to the values of its early days. Among these are a belief in individual freedom and democratic government and the promise of economic opportunity and progress for all people. The work for the United States is to keep its values of freedom, democracy and opportunity secure and vital in the 21st century.
美国已发生巨大变化从最初的13个鲜为人知的殖民地。人口300万人代表几乎每一个在世界上的民族和族裔群体。在经济，科技，文化，和社会继续取得进展。美国人生活在一个相互依存，相互联系的世界。美国仍然连接初期的价值。其中有一个信仰在个人自由和民主的政府和经济机会和各国人民的进步的承诺。对美国的工作，要保持其自由，民主和安全的机会和在21世纪的重要价值观。