[外语类试卷]大学英语六级模拟试卷566及答案与解析.doc
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1、大学英语六级模拟试卷 566及答案与解析 一、 Part I Writing (30 minutes) 1 For this part, you are allowed 30 minutes to write a short essay on the topic of Working at Home. You should write at least 150 words following the outline given below. 1目前许多人在家工作 2居家工作的利与弊 3我的看 法 Working at Home 二、 Part II Reading Comprehension
2、(Skimming and Scanning) (15 minutes) Directions: In this part, you will have 15 minutes to go over the passage quickly and answer the questions attached to the passage. For questions 1-4, mark: Y (for YES) if the statement agrees with the information given in the passage; N (for NO) if the statement
3、 contradicts the information given in the passage; NG (for NOT GIVEN) if the information is not given in the passage. 1 How to Solve Three Puzzles New knowledge and sophisticated diagnostic techniques are helping doctors recognize early signs of autism (孤独症 ), Alzheimers disease (痴呆症 ) and heart pro
4、blems in women. Harvard experts report on the advances that are giving patients hope. Detecting Autism Early diagnosis of autism is critical because educational programs that build upon a childs strengths and improve social skills may help sculpt the developing brain, minimizing the impact of the il
5、lness later in life. But spotting the disorder is hard since there is no test for it, although scientists are slowly uncovering gene abnormalities that make children vulnerable to autism. Last week The New England Journal of Medicine reported that a specific location on chromosome (染色体 ) 16 was the
6、site of mutations responsible for some cases of autism. For now, diagnosis depends on observing a childs behavior. Its a complex process, since no two cases are alike and signs range from mild to severe. Indeed, even though signs of autism may be apparent before their first birthday, most children a
7、rent diagnosed until the age of 3. That makes parents, who are so intimately familiar with their childs behavior, perhaps the most effective diagnostic “tools.“ The American Academy of Pediatrics recently issued screening guidelines recommending that pediatricians engage parents in evaluating infant
8、s for autism. Even babies developing typically, the guidelines say, should be screened at set intervals, such as during the 9-, 18- and 24-month visits. Healthy infants as young as 6 or 8 months do communicate and respond nonverbally to social cues. Most look up or turn at the sound of their names.
9、By 12 months they typically babble and point at objects. By 16 months they say single words; by 24 months, two-word phrases. In contrast, children with autism seldom make meaningful eye contact or respond to familiar voices. They may never speak. Their play is often repetitive and characterized by l
10、imited imagination (neatly arranging crayons instead of coloring with them). Others may simply flap their hands in excitement or disappointment. On their own, none of these signs means that a child has autism or another developmental disorder. Nevertheless, if your child has any of these signs, he o
11、r she merits evaluation. Although no treatments are curative, they can help children learn the skills they need to cope in a normal environment, achieve greater independence and have brighter futures. The Alzheimers Mystery Alzheimers disease, which begins years, even decades, before it causes sympt
12、oms, is a quietly ticking time bomb. But until recently doctors had no diagnostic test that could “hear“ the ticking. Unfortunately, it didnt matter much that Alzheimers couldnt be spotted early at a stage called mild cognitive impairment, or MCI since there were no treatments. Today, however, there
13、 are new diagnostic tests that can detect Alzheimers at an early stage, and several disease-modifying drugs are in advanced clinical trials. The brain shrinkage caused by Alzheimers can now be measured with volumetric magnetic resonance imaging (MRI). This technique takes a series of MRI brain scans
14、 and then uses sophisticated mathematical models to analyze the results. Most important, volumetric MRI enables researchers to identify subtle shrinkage in brain areas first affected by Alzheimers, such as the hippocampus, which is involved in memory. Another technology in limited clinical use is fl
15、uoro-deoxy-glucose positron emission tomography (FDG-PET). Images produced by FDG-PET reveal patterns of glucose metabolism (葡萄糖新陈代谢 ) in the cerebral cortex, the site of abstract thought, reasoning and learning. Because active neurons guzzle glucose for energy, diminished uptake in a specific patte
16、rn can denote Alzheimers. In the research setting, scientists have even used FDG-PET to identify people who do not yet have Alzheimers but are at risk for developing it, or for developing mild cognitive impairment. A different kind of PET-scan technology builds on recent discoveries about amyloid pl
17、aques and tau tangles, the neuron-killing proteins that accumulate in the brains of Alzheimers patients. Researchers at the University of Pittsburgh have developed Pittsburgh Compound-B, or PIB. When injected into the blood, this compound binds to amyloid plaques in the brain, allowing them to be de
18、tected on PET scans. PET scans with PIB clearly distinguish people with Alzheimers from healthy people. They may also help identify people with the progressive form of MCI. Taking a different approach, other researchers are identifying early changes in the levels of particular brain proteins in cere
19、brospinal fluid. (The clear spinal fluid constantly bathes the brain and spinal cord.) Spinal-fluid levels of the protein tau are typically elevated in Alzheimers, and an altered version of the tau protein, known as phosphorylated tau, can be detected early in Alzheimers. Lowered spinal-fluid concen
20、trations of an altered version of beta-amyloid, called A-42, are typical in Alzheimers and can also help identify people with mild cognitive impairment who are most likely to progress to Alzheimers. Although all these new imaging and biochemical developments are individually promising, the combinati
21、on of several different imaging tests and biochemical markers may yield the most accurate diagnosis. For example, scientists at the New York University School of Medicine have reported that combining volumetric MRI of the hippocampus with spinal-fluid measures of phosphorylated tau and isoprostane a
22、 marker of oxidative stress improved diagnostic accuracy in identifying people with mild cognitive impairment who are most likely to progress to Alzheimers. Heart Disease in Women When it comes to diagnosing the most common kind of heart disease, some cardiologists share Henry Higginss lament in My
23、Fair Lady: “Why cant a woman be more like a man?“ Thats because many women dont have the typical symptoms, like crushing chest pain and shortness of breath brought on by physical activity or stress. Instead, they have diffuse discomfort in the chest, unusual exhaustion or depression without an appar
24、ent reason. To make matters worse, the tests considered best at diagnosing coronary-artery disease generally dont work as well for women as they do for men. As a result, an alarming number of women with heart disease go undiagnosed and untreated despite repeated visits to the doctor and the emergenc
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