●Regionally, the Rocky Mountain states reported the most rapid growth rate - 37.1 percent since 1970 in a vast area with only 5 percent of the US population.

　　●Among states, Nevada and Arizona grew fastest of all: 63.5 and 53.1 percent respectively. Except fro Florida and Texas, the top 10 in rate of growth is composed of Western states with 7.5 million people - about 9 per square mile.

　　The flight from overcrowdedness affects the migration from snow belt to morebearable climates.

　　Nowhere do 1980 census statistics dramatize more the American search for spacious living than in the Far West. There, California added 3.7 million to its population in the 1970s, more than any other state.

　　In that decade, however, large numbers also migrated from California, mostly to other parts of the West. Often they chose - and still are choosing - somewhat colder climates such as Oregon, Idaho and Alaska in order to escape smog, crime and other plagues of urbanization in the Golden State.

　　As a result, California's growth rate dropped during the 1970s, to 18.5 percent - little more than two thirds the 1960s growth figure and considerably below that of other Western states.

　　63.Discerned from the perplexing picture of population growth the 1980 census provided, America in 1970s _____ .

　　A）enjoyed the lowest net growth of population in history

　　B）witnessed a southwestern shift of population

　　C）underwent an unparalleled period of population growth

　　D）brought to a standstill its pattern of migration since World dWar II

　　64.The census distinguished itself from previous studies on population movement in that _____ .

　　A）it stresses the climatic influence on population distribution

　　B）it highlights the contribution of continuous waves of immigrants

　　C）it reveals the Americans' new persuit of spacious living

　　D）it elaborates the delayed effects of yesterday's"baby boom"

　　65.We can see from the available statistics that _____ .

　　A）California was once the most thinly populated area in the whole US

　　B）the top 10 states in growth rate of population were all located in the West

　　C）cities with better climates benefited unanimously from migration

　　D）Arizona ranked second of all states in its growth rate of population

　　66.The word"demographers"（Line 1, Paragraph 8） most probably means _____ .

　　A）people infavor of the trend of democracy

　　B）advocates of migration between states

　　C）scientists engaged in the studey of population

　　D）conservatives clinging to old patterns of life

　　Passage 5

　　Scattered around the globe are more than 100 small regions of isolated volcanic activity known to geologists as hot spots. Unlike most of the world's volcanoes, they are not always found at the boundaries of the great drifting plates that make up the earth's surface; on the contrary, many of them lie deep in the interior of a plate. Most of the hot spots move only slowly, and in some cases the movement of the plates past them has left trails of dead volcanoes. The hot spots and their volcanic trails are milestones that mark the passage of the plates.