单选题 Although the United States cherishes the tradition that it is a nation of small towns and wide open spaces, only one in every eight Americans now lives on a farm. The recent population trend has been a double one, toward both urbanization and suburbanization. Metropolitan areas had grown explosively in the past decade, and nearly half this increase has been in the suburbs. With the rapid growth of cities has come equally rapid decentralization. The flight of Americans from the central city to the suburbs constituted one of the greatest migrations of modern times; quiet residential sections outside cities have become conglomerations (密集) of streets, split-level houses, and shopping centers.
This spurt of suburban expansion, however, does not alter tile basic fact that the United States has become one of the most urban nations on the face of the earth. Census (人口调查) Bureau figures show that the rural population has been shrinking steadily since 1830. When the United States became a nation it had no large cities at all; today some fifty cities have populations of more than 258,000. Mammoth complexes of cities are developing in the area of the East Coast and the east north central states, on the Pacific and Gulf coasts, and near the shores of the Great Lakes. Some sociologists now regard the entire 600-mile stretch between Boston and Washington D.C. an area holding a fifth of the country's population as one vast city or, as they call it, megalopolis.

单选题 A. traditional American belief is that ______.
A. few people live on farms
B. the nation consists mainly of small towns and wide open spaces
C. the population is the greatest in the world
D. the United States is a nation of big cities

单选题 The selection says that trends are toward the ______.
A. growth of cities and shrinking of suburban areas
B. growth of both rural and suburban areas
C. shrinking of urban and suburban areas
D. growth of urban and suburban areas

单选题 Nearly half the increase in metropolitan population is accounted for by the ______.
A. growth of small towns B. migration to farm areas
C. growth of the suburbs D. expansion of existing urban areas

单选题 The author implies that the modern suburb is ______.
A. quiet and residential B. very rural in character
C. confused and overgrown D. much like a small town

单选题 Megalopolis is the sociologist's name for a ______.
A. suburban area around a city
B. large city and its suburbs
C. group of towns organized as a city
D. group of cities blending to form one huge city