公共英语等级考试模拟公共英语PETS一级标准预测及参考9

公共英语(PETS)一级标准预测试卷及参考答案9More about Alzheimers DiseaseScientists have developed skin tests that may be used in the future to identify people with Alzheimers disease and may ultimately allow physicians to predict who is at risk of getting this neurological disorder.The only current means of diagnosing the disease in a living patient is a long and expensive series of tests that eliminate every other cause of dementia.“Since Aloes Alzheimer described the disease nearly a century ago, people have been trying to find a way to accurately diagnose it in its early stages,” said Patricia Grady, acting director of the National Institute of Neurological Disorders and Stroke in Bethesda, Maryland. “This discovery, if confirmed, could prove a big step forward in our efforts to deal with and understand the disease.”Alzheimers is the single greatest cause of mental deterioration in older people, affecting between 2.5 million and 4 million people in the United States alone. The devastating disorder gradually destroys memory and the ability to function, and eventually causes death. There is currently no known treatment for the disease.Researches discovered that the skin cells of Alzheimers patients have defects that interfere with their ability to regulate the flow of potassium in and out of the cells. The fact that the cell defects are present in the skin suggests that Alzheimers results from physiological changes throughout the body, and that dementia may be the first noticeable effect of these changes as the defects affect the cells in the brain, scientists said.The flow of potassium is especially critical in cells responsible for memory formation. The scientists also found two other defects that affect the cells supply of calcium, another critical element.One test developed by researches calls for growing skin cells in a laboratory culture and then testing them with an electrical detector to determine if the microscopic tunnels that govern the flow of potassium are open. Open potassium channels create a unique electrical signature.A spokesman for the Alzheimers Association said that if the validity of the diagnostic test can be proven it would be an important development, but cautioned that other promising tests for Alzheimers have been disappointing.1. The newly developed skin tests may be used in the future is to allow doctors toA. cure those with Alzheimers disease.B. discover the cause of Alzheimers disease.C. predict who might get Alzheimers disease.D. find the consequence of Alzheimers disease.2. The passage indicates that Alzheimers is a diseaseA. common to people, old and young.B. not costly to be cured.C. easy to be handled.D. not easy to be diagnosed.3. Which of the following statements about the Alzheimers disease is NOT true?A. It was so named because Aloes Alzheimer first described it.B. It is the greatest cause of mental deterioration in older people.C. It can destroy memory gradually and eventually cause death.D. There are many ways to deal with and cure the disease now.4. Which of the following about the relationship between Alzheimers and dementia is true?A. Dementia is one of the signs of AlzheimersB. Alzheimers is one of the causes of dementia.C. They are two completely different diseases.D. They are similar defects of the human brain.5. The last paragraph implies that the diagnostic testA. will not be as promising as others.B. is a very important development.C. may not be proven valid smoothly.D. will surely be disappointing in the end.New Attempts to Eradicate AIDS VirusA high-profile attempt to eradicate the AIDS virus in a few patients continues to show promise.But researchers wont know for a year or more whether it will work. , scientist David Ho told journalists here Wednesday for the Fourth Conference in Viruses and infections.“This is a study thats in progress,” says Ho, head of the Aaron Diamond AIDS Research Center, New York.The study involves 20 people who started combinations of anti-HIV drugs very early in the course of the disease, within 90 days of their infections. Theyve been treated for up to months. Four others have dropped out because of side effects or problems complying with the exacting drug system.The drugs have knocked the AIDS virus down to undetectable levels in the blood of all remaining patients. And, in the latest development, scientists have now tested lymph nodes and semen from a few patients and found no virus reproducing there, Ho says. “Bear in mind that undetectable does not equal absent，”He says.He has calculated that the drugs should be able to wipe out remaining virusesat least from known reservoirs throughout the bodyin two to three years. But the only way to prove eradication would be to stop the drugs and see if the virus comes back. On Wednesday, Ho said he wouldnt ask any patient to consider that step before 21/2 years of treatment.And he emphasized that he is not urging widespread adoption of such early, aggressive treatment outside of trials. No one knows the long-term risks.But other scientists are looking at similar experiments. A federally funded study will put 300 patients on triple-drug treatments and then see if some responding well after six months can continue to suppress the virus on just one or two drugs, says researcher Douglas Richman of the University of California, San Diego. Some patients in that study also may be offered the chance to stop therapy after months or more, he says.1. According to the passage, the attempt to eradicate the AIDS virusA. continues to be hopeful.B. Will be successful in a year.C. will be successful in future.D. will stop being hopeful.2. Which is NOT true about the study?A. There are 20 patients involved in the study.B. The patients have used several anti-HIV drugs.C. The patients have been treated for up to months.D. patients did not go through the whole study.3. What do Hes words “Bear in mind undetectable does not equal absent ”mean?A. AIDS virus can be undetectable in the blood.B. AIDS virus is undetectable in the blood.C. No AIDS virus can be detected in the blood.D. No virus found in the blood means no AIDS.4. How do we prove that the drugs have wiped out the remaining viruses?A. To use up all the drugs at once.B. To wait for the virus to die slowly.C. To ask the patients feeling about the disease.D. To stop the drugs to see if the virus comes back.5. Other scientists are looking at experiments that are similar in that they areA. costly.B. economical.C. traditional.D. bold.High Stress May Damage MemoryAccording to a report issued in May 98, elderly people who have consistently high blood levels of cortisol dont score as well on memory tests as their peers with lower levels of the stress hormone. Whats more, high levels of cortisol are also associated with shrinking of the hippocampus, a region of the brain that plays a key role in learning and memory.The findings suggest that even cortisol levels in the normal, “healthy ”range can actually accelerate brain aging.The study results “now provide substantial evidence that long-term exposure to adrenal stress hormones may promote hippocampal aging in normal elderly humans, ”write Nada Porter and Philip Landfield of the University of Kentucky in Lexington in their editorial. Cortisol is a hormone released in response to stress by the adrenal glands, which sit on top of the kidneys.Over a 5 to 6-year period. Dr. Sonia Lupien and his colleagues measured 24-hour cortisol levels in 51 healthy volunteers, most of whom were in their 70s.Despite wide variation in cortisol levels, the participants could be divided into three subgroups: those whose cortisol progressively increased over time and was currently high （increasing/high）; those whose cortisol progressively increased over time and was currently moderate （increasing/moderate）; and subjects whose cortisol decreased, but was currently moderate （decreasing/moderate）.The researchers tested the volunteers memory on six people in the increasing/high category and five people in the decreasing/moderate group. The groups did not differ on tests of immediate memory, but the increasing/high cortisol group had other memory problems compared with those in the decreasing/moderate group.The researchers also found that the total volume of the hippocampus in those in the increasing/high group was % lower than those in the decreasing/moderate group, although there were no differences in other brain regions.The results suggest that “. . . brain aging can be accelerated by levels of adrenal hormones that are not generally regarded as pathological and that variation within this normal range is related to variation in the rate of brain aging,” write Porter and Landfield. “This further suggests that chronic stress may accelerate the worsening of hippocampus.”1. The part of the brain important for a persons learning and memory isA. the cortisol.B. the adrenal glands.C. the stress hormo