A. state of being infected seriously B. state of being polluted seriously C. stafe of being made resistant to a war D. state of being made resistant to a disease 参考答案:D 答案解析:[解析]语义理解题。该字位于末段第一句:A good example of the exchange of medical ideas between east and west is that of
第28题: [单项选择]A、B两个港口,A在B的上游60千米处,甲、乙两船分别从A、B两港同时出发,都向上游航行。甲船出发时,有一物品掉落水中,浮在水面,随水流漂往下游。甲船出发航行一段后,调头去追落水的物品。当甲船追上落水物品时,恰好和乙船相遇。已知甲、乙两船在静水中的航行速度相同,且这个速度为水速的6倍。当甲船调头时,甲船已航行多少千米( ) A. 38千米 B. 30千米 C. 18千米 D. 25千米 参考答案:D 答案解析:[解析] 设水流速度为v,则甲、乙两船在静水中的航速为6v,则两船往上游航行时的船速应为6v-v=5v,甲船往下游航行的船速则为6v+v=7v。则甲船与乙船相遇的时间为60÷(5v+v)=10/v,此