（新课标）2018年高三英语一轮复习 题组层级快练14 Unit 4 Astronomy the science of the stars 新人教版必修3.docVIP

题组层级快练14 Unit 4 Astronomy the science of the stars “阅读＋七选五＋完形”组合练(时间：35分钟)Ⅰ.阅读理解阅读下列短文从每题所给的四个选项(A、B、C和D)中选出最佳选项。(原创)A new study shows a vaccine designed to prevent dengue fever(登革热)could actually be making people sick. Dengue infects an estimated 400 million people worldwide each year. The virus spreads to human beings through the bite of an insect, ito. Most people who get dengue suffer health problems like those resulting from a mild case of influenza, like a higher than normal body temperature. But the illness is more severe the second time a person gets it. In serious cases, it can cause bleeding inside the body and even death. About 25，000 people a year die from the infection. The drug Dengvaxia is so far the only vaccine approved for use against dengue. Several countries — including Brazil, Mexico, Costa Rica, Paraguay and the Philippines — have already approved use of the drug. Trials of Dengvaxia involved more than 30，000 people in 10 countries. Among young people, the drug was found to reduce infections by 60 percent, and hospitalizations by 80 percent. But over time, many of those vaccinated got seriously ill with dengue. Researchers from Britain and the United States studied the results of the tests. They found the vaccine acted as a first infection in people who had not had the virus before. The researchers reported their findings in the journal Science. They say they are concerned that people who get infected a second time after the vaccine can get severely sick. The study found that the vaccine should not be a problem in countries with many cases of dengue. In such areas, Dengvaxia was found to reduce severe sickness and hospitalizations by 20 percent to 30 percent. But the researchers warned that in countries where only 10 percent of people have been infected with dengue, the vaccine needs to be carefully used. Ideally, Rodriguez瑽arraquer said, people should be tested before getting vaccinated, to see if they have been infected in the past. 1. Ho