题目

长期吸食或注射毒品会危及人体健康，下列各组中都属于毒品的是A．冰毒、黄连素      B．海洛因、黄连素  C．大麻、摇头丸      D．黄曲霉素、尼古丁  答案：C解析: My English teacher insisted that the exercises ____very difficult and that we ____them carefully.A．were; must finish B．be; finish C．were; finish D．be; finished