7、rationB.whypeoplechosetomovetoAmericaC.therapidgrowthofthepopulationofAmericaD.whatimmigrantshavebroughttoAmerica答案 A [细节理解题。根据短文Americanimmigrationbeganin1607withthecolony(殖民地)ofJamestown.以及下文可知第二段主要讲的是美国移民的历史,故选A。]2.Severalfoodsarementionedinthetexttoshow________.A