题目

Occupy Wall Street protests, which started in New York in mid—September and ___to dozens of US cities, have shown the anger of Americans over the economic problems．        A．has spread        B．will spread            C．have spread                                D．had spread 答案：C 某校共有学生1600人，色盲遗传病调查研究后发现，该群体中色盲基因的频率是6.8％，780名女生中有患者23人、携带者52人，男生中色盲的人数约为： [　　] A．120 B．119 C．64 D．56