单项选择题
Up to the end of WW II,there were（）waves of large-scale emigration to the United States.
A.four B.two C.three D.None of the above
单项选择题 The population between the age of 25 and 44 increased by 28.1%from 1980 to 1989 because（）
单项选择题 More than（）of the population in the United States lived in city areas in 1988.
单项选择题 One of the reasons for the growth of population in Florida is because of its（）
