王迈迈英语

ore throat and body aches come on suddenly and are more severe than cold symptoms.

　　The ALA notes that it may be particularly difficult to tell when infants and preschool age children have the flu. It advises parents to call the doctor if their small children have flu-like symptoms.

　　Both cold and flu symptoms can be eased with over-the-counter medications as well. However,children and teens with a cold or flu should not take aspirin for pain relief because of the risk of Reye syndrome(综合症)，a rare but serious condition of the liver and central nervous system.Reye syndrome .

　　There is, of course, no vaccine for the common cold. But frequent hand washing and avoiding close contact with people who have colds can reduce the likelihood of Catching one.

　　21. According to the author, knowing the cause of the misery will help

　　A) prevent people from catching colds and the flu

　　B) the patient obtain cheaper prescription drugs

　　C) the patient buy medicine over the counter

　　D) shorten the duration of the illness

　　22. We learn from the passage that

　　A) over-the-counter drugs can be taken to ease the misery caused by a cold or the flu

　　B) one doesn't need to take any medicine if he has a cold or the flu

　　C) aspirin should not be included in over-the-counter medicines for the flu

　　D) delayed treatment of the flu will harm the liver and central nervous system

　　23. According to the passage, to combat the flu effectively,

　　A) one should take medicine upon catching the disease

　　B) one should identify the virus which causes it

　　C) one should consult a doctor as soon as possible

　　D) one should remain alert when the disease is spreading

　　24. Which of the following symptoms will distinguish the flu from a cold?

　　A) A sore throat.

　　B)A stuffy nose.

　　C) A dry cough.

　　D) A high temperature.

　　25. If children have flu-like symptoms, their parents

　　A) are encouraged to take them to hospital for vaccination

　　B) are advised not to give them aspirin

　　C) should watch out for signs of Reye syndrome

　　D) should prevent them from mixing with people running a fever

　　
Passage FOUR
 Questions 21 to 25 are based on the following passage.

　　Lead deposits, which accumulated in soil and snow during the 1960's and 70's, were primarily the result of leaded gasoline emissions originating in the United States. In the twenty years that the Clean Air Act has mandated unleaded gas use in the United States, the lead accumulation world-wide has decreased significantly.

　　A study published recently in the journal Nature shows that air-borne leaded gas emissions from the United States were the leading contributor to the high concentration of lead in the snow in Greenland. The new study is a result of the continued research led by Dr. Charles Boutron, an expert on the impact of heavy metals on the environment at the National Center for Scientific Research in France. A study by Dr. Boutron published in 1991 showed that lead levels in arctic(北极的) snow were declining.

　　In his new study, Dr. Boutron found the ratios of the different forms of lead in the leaded gasoline used in the United States were different from the ratios of European, Asian and Canadian gasolines and thus enabled scientists to differentiate ( 分区) the lead sources. The dominant lead ratio found in Greenland snow matched that found in gasoline from the United States.

　　In a study published in the journal Ambio, scientists found that lead levels in soil in the North-eastern United States had decreased markedly since the introduction of unleaded gasoline.

　　Many scientists had believed that the lead would stay in soil and snow for a longer period.

　　The authors of the Ambio study examined samples of the upper layers of soil taken from the same sites of 30 forest floors in New England, New York and Pennsylvania in 1980 and in 1990.

　　The forest environment processed and redistributed the lead faster than the scientists had expected.

　　Scientists say both studies demonstrate that certain parts of the ecosystem (生态系统 ) respond rapidly to reductions in atmospheric pollution, but that these findings should not be used as a license to pollute.

　　26. The study published in the journal Nature indicates that

　　A) lead deposits in arctic snow are on the increase

　　B) the Clean Air Act has not produced the desired results