题目

_____ many times, but he still didn’t know what to do next.       A. Having been told                                        B. Although he had been told   C. He had been told                                        D. Having told 答案：C德国科学家西诺西和吕克·蒙塔尼因发现遗传物质是RNA的艾滋病病毒（HIV）而获得2008年诺贝尔生理学或医学奖。下列关于生物体内的RNA叙述错误的是  （    ）         A．生物的遗传物质只能是DNA或者是RNA        B．RNA具有多种生理功能，如遗传功能、催化功能等        C．HIV是通过病毒RNA的自我复制能在T细胞外完成增殖        D．RNA分子中含有核糖，DNA分子中含有脱氧核糖