Section A Exploring the World Text AA Brief Introduction to the USA Note The United States of America (commonly referred to as the United States,the U.S.,the USA,or America)is a federal constitutional republicl comprising fifty states and a federal district.The country is situated mostly in central North America,where its forty-eight contiguous states and Washington,D.C.,the capital district,lie between the Pacific and Atlantic Oceans,bordered by Canada to the north and Mexico to the south.The state of Alaska is in the northwest of the continent,with Canada to its east and Russia to the west across the Bering Strait.The state of Hawaii is an archipelago in the mid-Pacific.The country also possesses several territories,or insular areas,in the Caribbean and Pacific. The coastal plain of the Atlantic seaboard gives way further inland to deciduous forests and the rolling hills of the Piedmont.The Appalachian Mountainsl21 divide the eastern seaboard from the Great Lakes and the grasslands of the Midwest.The Mississippi-Missouri River,the world's fourth longest river system,runs mainly north-south through the heart of the country.The flat,fertile prairie of the Great Plains stretches to the west,interrupted by a highland region in the southeast.The Rocky Mountains,at the western edge of the Great Plains,extend north to south across the country,reaching an altitude of higher than 14,000 feet(4,300 m)in Colorado.Farther west is the rocky Great Basin and deserts such as the Mojave.Alaska's Mount McKinley is the country's tallest peak.Active volcanoes are common throughout Alaska's Alexander and Aleutian Islands,and Hawaii consists of volcanic islands.The super volcano underlying Yellowstone National Park in the Rockies is the continent's largest volcanic feature. 大连理工大学出版社大连理工大学出版社 Section A Exploring the World Text A A Brief Introduction to the USA The United States of America (commonly referred to as the United States, the U.S., the USA, or America) is a federal constitutional republic[1] comprising fifty states and a federal district. The country is situated mostly in central North America, where its forty-eight contiguous states and Washington, D. C., the capital district, lie between the Pacific and Atlantic Oceans, bordered by Canada to the north and Mexico to the south. The state of Alaska is in the northwest of the continent, with Canada to its east and Russia to the west across the Bering Strait. The state of Hawaii is an archipelago in the mid-Pacific. The country also possesses several territories, or insular areas, in the Caribbean and Pacific. The coastal plain of the Atlantic seaboard gives way further inland to deciduous forests and the rolling hills of the Piedmont. The Appalachian Mountains[2] divide the eastern seaboard from the Great Lakes and the grasslands of the Midwest. The Mississippi-Missouri River, the world’s fourth longest river system, runs mainly north- south through the heart of the country. The flat, fertile prairie of the Great Plains stretches to the west, interrupted by a highland region in the southeast. The Rocky Mountains, at the western edge of the Great Plains, extend north to south across the country, reaching an altitude of higher than 14, 000 feet (4, 300 m) in Colorado. Farther west is the rocky Great Basin and deserts such as the Mojave. Alaska’s Mount McKinley is the country’s tallest peak. Active volcanoes are common throughout Alaska’s Alexander and Aleutian Islands, and Hawaii consists of volcanic islands. The super volcano underlying Yellowstone National Park in the Rockies is the continent’slargest volcanic feature. Note