IV. Reading Comprehension (60 points) Directions: There are five reading passages in this part. Each passage is followed by four questions. For each question there are four suggested answers marked A, B, C and D. Choose one best answer and blacken the corresponding letter on the Answer Sheet. Passage One Wild and farm birds often get a flu virus. Yet they usually are able to carry the virus without getting sick. In 1997 six people in Hong Kong died of a different kind of bird flu virus. It is called the h-five-n-one virus. The Hong Kong government quickly ordered the killing of all farm birds there. That stopped the spread of h-five-n-one to people in Hong Kong. Yet the virus bad already spread to other parts of Asia. It was found in 16 countries between 2003 and 2006. The h-five-n-one virus first appeared in Africa. This raised many concerns about the spread of the disease. Scientists do not know exactly how bird flu came to Africa. At first, they thought wild birds were to blame. Now, officials with the U. N. Food and Agriculture Organization believe the main cause is trade in farm birds. The bird flu virus is found in the waste and liquids of infected birds. The virus spreads when healthy birds or people touch sick birds or nay infected (被感染了的) part of sick birds. Right now, the virus is not spreading among person to person. But the virus could change and start spreading among people. Health officials believe that it is even more possible now that bird flu has spread in Africa, and that is why international organizations are working so hard to stop its spread. The best way to stop the spread of bird flu is to kill all the chickens in an area where bird flu has been discovered. More than 145 000 chickens have been killed in Nigeria since bird fin was first found one year ago. 36. The passage focuses on ______.