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Questions 21 to 22 are based on the following news. At the end of the news item, you will be given 10 seconds to answer the questions. Now, listen to the news. According to this news, why did so many people from all over the world travel to New York
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Just as Roman gladiators drank the blood of foes to gain strength, modem Olympians have infused the blood of their own to gain endurance. Blood doping, which tainted the triumphs of some Olympians, has at last been banned. Blood doping, in short, means withdrawal of one unit of a little more of blood from an athlete’s system about four to six weeks before a competition. The blood is then stored in a frozen state while the body replenished the lost blood through natural processes. The extracted blood is unfrozen and then pumped back into the athlete’s system just before the competition. This increases the body’s hemoglobin count, hereby increasing the capacity for oxygen delivery and raising the level of endurance. A recent colloquium on the ethics of blood doping, summarized in The Physician and Sports Medicine, cited eases of runners getting blood transfusions so they could run fast enough to qualify for Boston Marathon and of blood doping in dog and horse racing. Blood doping may be surprisingly common among world-class endurance athletes, especially cyclists and runners. Blood doping is cheating and it is now banned by the International Olympic Committee, but it is still impossible to test, and till sure checks are found, one can only count on the personal ethics of the sportspersons concerned. Does blood doping really work Buick et al. and Williams et al. have made some studies in the laboratory. In one study, 11 highly trained male track athletes underwent extensive treadmill testing before and alter phlebotomy with re-infusion of 900mi of antilogous freeze-preserved red cells. The blood doping increased the mean hemoglobin concentration 8% (from 15.1% to 16.3% gnm/100ml) , maximal oxygen consumption 5% , and running time to exhaustion 35%. In another study, 12 experienced male distance runners who received 920ml of antilogous blood had a mean 7% increase in hemoglobin concentration and a mean 45-second improvement in time on a 5-mile treadmill run, compared with results after they received 920m1 saline. In the third study, 9 male college students who received two units antilogous blood had a significant increase in hemoglobin concentration and maximal oxygen consumption on a cycle ergo-meter. It is reasonable to conclude that blood doping does work when properly performed in the laboratory. But does it work in the field The problem in determining if blood doping works in the field is that almost all the reports are anecdotal. Whether it works or not, blood doping as it was done for the U.S. Olympic cyclists is to be condemned. Three of the cyclists developed flu-like symptoms 36 hours after transfusion, and one of them, when asked about blood doping, said, "Yeah, I did it. I got sick and it ruined me for the Olympics." To be sure, some of the cyclists who blood-doped won medals, but so did some who refused blood doping. Likewise, not all Olympians who admitted to blood doping were medal winners: an Italian runner who blood-doped for the marathon said he ran poorly and the national cross-country team alleged to have blood-doped ran poorly. In short, one cannot tell from anecdotal reports whether or not blood doping works in the field. Blood doping is banned because
Questions 1 to 3 are based on the following conversation. At the end of the conversation, you will be given 15 seconds to answer the questions. Now, listen to the conversation. What is implied from the professor’s words after the student’s explanations of the mistake’
Three factors contribute to the miraculous spread of English (31) an international language: English usage in science, technology and commerce; the ability to (32) vocabulary from other languages; and the acceptability of various English dialects. In science, English (33) German after World War II. With this technical and scientific dominance (34) the beginning of overall dominance by the language, (35) in Europe and then globally. Today, the information (36) has replaced the industrial age and has (37) time and distance. This is transforming world economies from industrial production to information-based goods and services. (38) geography and borders, the information revolution is reflecting our world. In less than twenty years, information processing, (39) limited to the printed work, has given way to computers and the Internet. Computer-aided communication is closing the gap between spoken and written English. It encourages more (40) conversational language and a tolerance for diversity and individual style. English, (41) many languages, uses a phonetic alphabet and fairly basic grammar. But most importantly, it has a large and extensive vocabulary, (42) about 80% is foreign. It has borrowed and continues to borrow words from Spanish and French, Hebrew and Arabic, Hindi-Urdu and Bengali, Malay and Chinese, (43) from languages from West Africa and Polynesia. This language characteristic makes it unique (44) history. Finally, (45) English language central authority guards the standards of the language; therefore, many (46) have developed: American, British, Canadian, Indian, and Australian, (47) a few. There is no standard pronunciation. But within this diversity is a (48) of grammar and one set of core vocabulary. (49) , each country that speaks the language can introduce (50) of its own culture into the usage and vocabulary.
设函数f(x)(x≥0)连续可导，且f(0)=1．又已知曲线y=f(x)、x轴、y轴及过点(x，0)且垂直于x轴的直线所围成的图形的面积与曲线y=f(x)在[0，x]上的一段弧长相等，求f(x)．
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