单项选择题
According to historians and specialists in demography,there are（）great population movement(s)in the history of the United States.
A.four B.three C.five D.None of the above
单项选择题 During the third wave of immigration from 1890 to 1910,many came from（）
单项选择题 Between 1845 and 1854,about 1.5 million Irishmen emigrated to United States because of（）
单项选择题 Up to the end of WW II,there were（）waves of large-scale emigration to the United States.
