2．The World Health Organization reports a number of people have died of the Ebola virus in central Africa during the last few months．Ebola，also known as Ebola hemorrhagic （出血） fever or Ebola viral disease．is a rare and deadly illness with high death rates in humans and primates．The natural source of Ebola virus remains unknown，although bats seem to be the most likely source．
The Ebola virus began spreading after victims were discovered in northeastern Cabon．So far，it is the third time Ebola has spread through Cabon since 1994．Health officials believe people moving across the border spread the disease from Cabon co Congo Ebola is highly infectious and kills up to 80% of its victims．Researchers do not know the method with which the virus first appears in humans，but they believe it is through infected animals．The disease then spreads from person to person through blood and other body liquids．
Ebola victims treated early have the base chance of survival．Signs of Ebola include a high temperature，diarrhea，muscle pains and bleeding inside the body．in severe cases，victims experience chest pains and death．There is no known cure for the disease and no way yet to prevent it．
Scientists at the American National institutes of Health are working to develop a vaccine（疫苗） to prevent Ebola．Doctor Cary Nobel is leading the research effort at N-l-H testing center in the eastern state of Maryland．He says that during the past two years，the vaccine has been tested on small animals and monkey a for safety and effectiveness．
In the most recent study，four monkeys who had been given the vaccine were completely protected from a deadly injection of the Ebola virus．the study was described in November in Nature magazine．Doctor Nobel says the tests appear to have moved scientists one step closer to a vaccine for humans．
28．Where does the Ebola virus come fromD？
A．Bats．B．Monkeys．C．Infected humans．D．Something unknown．
29．When infected with Ebola virus，people may experience the following exceptA．
A．heart attack B．a rise in temperature
C．chest pains D bleeding inside the body
30．What can we learn from the passageB？
A．Once infected with the Ebola virus．people can never survive．
B．Half of the Ebola victims will lose their lives．
C．No cure has been found for the disease．
D．Scientists have succeeded in preventing Ebola．
31．What is Doctor Nobel's attitude towards the testsB？
A．Discouraged．B．Positive．C．Doubtful．D．Not mentioned．
分析 本文属于说明文阅读，作者通过这篇文章主要向我们描述了埃博拉病毒给人类造成的巨大伤害，它的传染性很强，主要通过血液和体液传播，患病者死亡率极高，只有在患病初期有痊愈的机会，世界卫生组织已经研究了疫苗，目前已在动物身上试验，有待下一步动作．
解答 28．D．细节理解题．根据文章第一段"The natural source of Ebola virus remains unknown，although bats seem to be the most likely source"，埃博拉病毒的天然来源仍然未知，尽管蝙蝠似乎是最有可能的来源；故选D．
29．A．细节理解题．根据文章第三段"Signs of Ebola include a high temperature，diarrhea，muscle pains and bleeding inside the body．in severe cases，victims experience chest pains and death"，埃博拉病毒的标志包括高温、腹泻、肌肉疼痛和身体内出血，严重的情况下，受害者经历胸痛和死亡；故选A．
30．B．细节理解题．根据文章第三段"Health officials believe people moving across the border spread the disease from Cabon co Congo Ebola is highly infectious and kills up to 80% of its victims"卫生官员相信人跨越边境传播的埃博拉病毒的传染性很强，病人死亡率达80%；故选B．
31．B．推理判断题．根据文章最后一段"Doctor Nobel says the tests appear to have moved scientists one step closer to a vaccine for humans"，诺贝尔医生说，这些测试结果的出现正推动科学家们一步一步接近人类的疫苗，可推测他的态度是积极的；故选B．
点评 考察学生的细节理解和推理判断能力，做细节理解题时一定要找到文章中的原句，和题干进行比较，再做出正确的选择．在做推理判断题不要以个人的主观想象代替文章的事实，要根据文章事实进行合乎逻辑的推理判断．
