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单选题Medicine depends on other fields for basic information, particularly some of their specialized branches. A. conventionally B. obviously C. especially D. inevitably
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单选题The new theory was corroborated.
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单选题The turbulence detector can tell the severity of the turbulence by measuring
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单选题During their winter hibernation period, bears doze .
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单选题{{B}}第二篇{{/B}} {{B}} External Rewards{{/B}} Psychologists take opposing views of how external rewards, from warm praise to cold cash, affect motivation and creativity. Behaviorists, who study the relation between actions and their consequences, argue that rewards can improve performance at work and school. Cognitive (认识学派的) researchers, who study various aspects of mental life, maintain that rewards often destroy creativity by encouraging dependence on approval and gifts from others. The latter view has gained many supporters, especially among educators. But the careful use of small monetary (金钱的) rewards sparks creativity in grade-school children, suggesting that properly presented inducements (刺激) indeed aid inventiveness, according to a study in the June Journal of Personality and Social Psychology. "If kids know they're working for a reward and can focus on a relatively challenging task, they show the most creativity," says Robert Eisenberger of the University of Delaware in New York. "But it's easy to kill creativity by giving rewards for poor performance or creating too much anticipation for rewards." A teacher who continually draws attention to rewards or who hands out high grades for ordinary achievement ends up with uninspired students, Eisenberger holds. As an example of the latter point, he notes growing efforts at major universities to tighten grading standards and restore failing grades. In earlier grades, the use of socalled token economies, in which students handle challenging problems and receive performancebased points toward valued rewards, shows promise in raising effort and creativity, the Delaware psychologist claims.
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单选题Spelling and Writing There is a popular belief among parents that schools are no longer interested in spelling. No school I have taught in has ever ignored spelling or considered it unimportant as a basic skill. There are, however, vastly different ideas about how to teach it, or how much priority(优先) it must be given over general language development and writing ability. The problem is, how to encourage a child to express himself freely and confidently in writing without holding him back with the complexities of spelling? If spelling becomes the only focal point of his teacher"s interest, clearly a bright child will be likely to "play safe". He will tend to write only words within his spelling range, choosing to avoid adventurous language. That"s why teachers often encourage the early use of dictionaries and pay attention to content rather than technical ability. I was once shocked to read on the bottom of a sensitive piece of writing about a personal experience: "This work is terrible! There are far too many spelling errors and your writing is illegible (难以辨认的)." It may have been a sharp criticism of the pupil"s technical abilities in writing, but it was also a sad reflection on the teacher who had omitted to read the essay, which contained some beautiful expressions of the child"s deep feelings. The teacher was not wrong to draw attention to the errors, but if his priorities had centered on the child"s ideas, an expression of his disappointment with the presentation would have given the pupil more motivation to seek improvement.
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单选题The project required ten years of {{U}}diligent{{/U}} research.
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单选题It is absurd to predict that the sun will not rise tomorrow.
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单选题I don't why everything around me is going int confusion.A. considerationB. puzzleC. attractionD. contradiction
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单选题I have been trying to give up smoking.A. give offB. put upC. quitD. accept
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单选题下面有3篇短文,每篇短文后有5道题。请根据短文内容,为每题确定1个最佳选项。{{B}}第一篇{{/B}} Hair Detectives Scientists have found a way to use hair to figure out where a person is from and where that person has been. The finding could help solve crimes, among other useful applications. Water is central to the new technique. Our bodies break water down into its parts: hydrogen(氢)and oxygen. Atoms (原子) of these two elements end up in our tissues and hair. But not all water is the same. Hydrogen and oxygen atoms can vary in how much they weigh. Different forms of a single element are called isotopes(同位素). And depending on where you live, tap water contains unique proportions of the heavier and lighter isotopes of hydrogen and oxygen. Might hair record these watery quirks(古怪举动;怪僻). That's what James R. Ehleringer, an environmental scientist at the University of Utah in Salt Lake City, wondered. To find out, he and his colleagues collected hair from barbers and hair stylists(发型师)in 65 cities in 18 states across the United States. The researchers assumed that the hair they collected came from people who lived in the area. Even though people drink a lot of bottled water these days, the scientists found that hair overwhelmingly(压倒性地) reflected the concentrations of hydrogen and oxygen isotopes in local tap water. That's probably because people usually cook their food in the local water. What's more, most of the other liquids people drink including milk and soft drinks contain large amounts of water that also come from sources within their region. Scientists already knew how the composition of water varies throughout the country. Ehleringer and colleagues combined that information with their results to predict the composition of hair in people from different regions. One hair sample used in Ehleringer's study came from a man who had recently moved from Beijing, China, to Salt Lake City. As his hair grew, it reflected his change in location. The new technique can't point to exactly where a person is from, because similar types of water appear in different regions that span a broad area. But authorities can now use the information to analyze hair samples from criminals or crime victims and narrow their search for clues(线索).
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单选题You must be tired, but try to hang on till all the work"s finished.
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单选题Cell Phone Lets Your Secret Out Your cell phone holds secrets about you. Besides the names and (51) that you've programmed into it, traces of your DNA linger (逗留) on the device, according to a new study. DNA is genetic material that (52) in every cell. Like your fingerprint, your DNA is unique to you (53) you have an identical twin. Scientists today routinely analyze DNA in blood, saliva (唾液), or hair left (54) at the scene of a crime. The results often help detectives identify (55) and their victims. Your cell phone can reveal more about you (56) you might think. Meghan J. McFadden, a scientist at McMaster University in Hamilton, Ontario, heard about a crime in which the suspect bled onto a cell phone and later dropped the (57) . This made her wonder whether traces of DNA lingered on cell phones—even when no blood was involved (58) she and colleague Margaret Wallace of the City University of New York analyzed the flip-open phones of 10 volunteers. They used swabs (药签) to collect (59) traces of the users from two parts of the phone: the outside, where the user holds it, and the (60) , which is placed at the user's ear. The scientists scrubbed the phones using a solution made mostly (61) alcohol. The aim of washing was to remove all detectable traces of DNA. The owners got their phones (62) for another week. Then the researchers collected the phones and repeated the swabbing of each phone once more. The scientists discovered DNA that (63) to the phone's speaker on each of the phones. Better samples were collected from the outside of each phone, but those swabs also picked up DNA that belonged to other people who had apparently also handled the phone. (64) , DNA showed up even in swabs that were taken immediately after the phones were scrubbed (擦洗). That suggests that washing won't remove all traces of evidence from a criminal's device. So cell phones can now be added to the (65) of clues that can decide a crime-scene investigation.
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单选题 Night of the Living Ants When an ant dies, other ants move the dead insect out of the nest. This behavior is interesting to scientists, who wonder how ants know for sure—and so soon—that another ant is dead. Dong-Hwan Choe, a scientist at the University of California found that Argentine ants have a chemical on the outside of their bodies that signals to other ants, "I'm dead—take me away." But there's a twist to Choe's discovery. These ants are a little bit like zombies (僵尸). Choe says that the living ants—not just the dead ones—have this death chemicals. In other words, while an ant crawls around, perhaps in a picnic or home, it's telling other ants that it's dead. What keeps ants from hauling away the living dead? Choe found that Argentine ants have two additional chemicals on their bodies, and these tell nearby ants something like, "Wait—I'm not dead yet," So Choe's research turned up two sets of chemical signals in ants: one says, "I'm dead," the other set says," I'm not dead yet." Other scientists have tried to figure out how ants know when another ant is dead. If an ant is knocked unconscious, other ants leave it alone until it wakes up. That means ants know that unmoving ants can still be alive. Choe suspects that when an Argentine ant dies, the chemical that says "Wait—I'm not dead yet" quickly goes away. Once that chemical is gone, only the one that says "I'm dead" is left. "It's because the dead ant no longer smells like a living ant that it gets carried to the graveyard (墓地), not because its body releases new unique chemicals after death," said Choe. When other ants detect the "dead" chemical without the "not dead yet" chemical, they haul away the body. This was Choe's hypothesis (假设). To test his hypothesis, Choe and his team put different chemicals on Argentine ant pupae (蛹). When the scientists used the "I'm dead" chemical, other ants quickly hauled the treated pupae away. When the scientists used the "Wait—I'm not dead yet" chemicals, other ants left the treated pupae alone. Choe believes this behavior shows that the "not dead yet" chemicals override (优先于) the "dead" chemical when picked up by adult ants. And that when an ant dies, the "not dead yet" chemicals fade away. Other nearby ants then detect the remaining "dead" chemical and remove the body from the nest.
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单选题He was rather vague about the reasons why he never finished school.
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单选题Sugar Power for Cell Phones Using enzymes commonly found in living cells, a new type of fuel cell produces small amounts of electricity from sugar. If the technology is able to succeed in mass production, you may some day share your sweet drinks with your cell phone. In fuel cells, chemical reactions generate electrical currents. The process usually relies on precious metals, such as platinum. In living cells, enzymes perform a similar job, breaking down sugars to obtain electrons and produce energy. When researchers previously used enzymes in fuel cells, they had trouble keeping them active, says Shelley D. Minteer of St Louis University. Whereas biological cells continually produce fresh enzymes, there's no mechanism in fuel cells to replace enzymes as they quickly degrade. Minteer and Tamara Klotzbach, also of St Louis University, have now developed polymers that wrap around an enzyme and preserve it in a microscopic pocket. "We tailor these pockets to provide the ideal microenvironment" for the enzyme, Minteer says. The polymers keep the enzyme active for months instead of days. In the new fuel cell, tiny polymer bags of enzyme are embedded in a membrane that coats one of the electrodes. When glucose from a sugary liquid gets into a pocket, the enzyme oxidizes it, releasing electrons and protons. The electrons cross the membrane and enter a wire through which they travel to the other electrode, where they react with oxygen in the atmosphere to produce water. The flow of electrons through the wire constitutes an electrical current that can generate power. So far, the new fuel cells don't produce much power, but the fact that they work at all is exciting, says Paul Kenis, a chemical engineer at the University of Illinois at Urhana-Champaign. "Just getting it to work," Kenis says, "is a major accomplishment." Sugar-eating fuel cells could be an efficient way to make electricity. Sugar is easy to find. And the new fuel cells that run on it are biodegradable, so the technology wouldn't hurt the environment. The scientists are now trying to use different enzymes that will get more power from sugar. They predict that popular products may be using the new technology in as little as 3 years.
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单选题What is the Coolest Gas in the Universe? What is the coldest air temperature ever recorded on the Earth? Where was this low temperature recorded? The coldest recorded temperature on Earth was -91℃, which 1 in Antarctica(南极洲) in 1983. We encounter an interesting situation when we discuss temperatures in 2 . Temperatures in Earth orbit(轨道) actually range from about +120℃ to -120℃. The temperature depends upon 3 you are in direct sunlight or in shade. Obviously, -120℃ is colder than our body can 4 endure. The space temperatures just discussed affect only our area of the solar 5 . Obviously, it is hotter closer to the Sun and colder as we travel 6 from the Sun. Scientists estimate temperatures at Pluto are about -210℃. How cold is the lowest estimated temperature in the entire universe? Again, it depends upon your 7 . We are taught it is supposedly 8 to have a temperature below absolute zero, which is -273℃, at which atoms do not move. Two scientists, Cornell and Wieman, have successfully 9 down a gas to a temperature barely above absolute zero. They won a Nobel Prize in Physics in 2001 for their work—not a discovery, in this case. Why is the two scientists" work so important to science? In the 1920s, Satyendra Nath Bose was studying an interesting 10 about special light particles (颗粒) we now call photons (光子). Bose had trouble 11 other scientists to believe his theory, so he contacted Albert Einstein. Einstein"s calculations helped him theorize that atoms 12 behave as Bose thought—but only at very cold temperatures. Scientists have also discovered that ultra-cold (超冷) atoms can help them make the world"s atomic clocks even 13 accurate. These clocks are so accurate today they would only lose one second 14 six million years! Such accuracy will help us travel in space because distance is velocity times time(d=vt). With the long distances involved in space 15 , we need to know time as accurately as possible to get accurate distance.
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单选题The park gave the whale to the Foundation and big contributions came from all parts of the world. A. dominations B. denotation C. donations D. signatures
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单选题{{B}}第三篇{{/B}} {{B}}A Phone that Knows You're Busy{{/B}} It's a modem conundrum: you're too busy to be disturbed by incessant phone calls so you mm your cell phone off. But if you don't remember to turn it back on when you're less busy, you could miss some important calls. If only the phone knew when it was wise to interrupt you, you wouldn't have to turn it off at all. Instead, it could let calls through during spells of relative inactivity. A bunch of behavior sensors and a clever piece of software could do just that, by analyzing your behavior to determine if it's a good time to interrupt you. If built into a phone, the system may decide you're too busy and ask the caller to leave a message or ring back later. In a desktop computer, the system could stop instant messages or spain annoying you when you're busy. James Fogarty and Scott Hudson at Camegie Mellon University in Pennsylvania based their system on tiny microphones, cameras and touch sensors that reveal body language and activity. First they had to study different behaviors to find out which ones strongly predict whether your mind is interrupted. The potential "busyness" signals they focused on included whether the office doors were left open or closed, the time of day, if other people were with the person in question, how close they were to each other, and whether or not the computer was in use. The sensors monitored these and many other factors while four subjects were at work. At random intervals, the subjects rated how in term ptible they were on a scale ranging from "highly interruptible" to "highly not—term ptible". Their ratings were then correlated with the various behaviors. "It is a shotgun approach: we used all the indicators we could think of and then let statistics ferret out which were important," says Hudson. The model showed that using the keyboard, and talking on a landline or to someone else in the office correlated most strongly with how interruptible the subjects judged themselves to be. Interestingly, the computer was actually better than people at predicting when someone was too busy to be interrupted. The computer got it right 82 per cent of the time, humans 77 percent. Fogarty speculates that this might be because people doing the interrupting are inevitably biased towards delivering their message, whereas computers don't care. The first application for Hudson and Fogarty's system is likely to be in an instant messaging system, followed by office phones and cell phones. "There is no technological roadblock to it being deployed in a couple of years," says Hudson.
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单选题The Forbidden Apple New York used to be the city that never sleeps. These days, it"s the city that never smokes, drinks or does anything naughty (at least, not in public). The Big Apple is quickly turning into the Forbidden Apple. If you wanted a glass of wine with your picnic in Central Park, could you have one? No chance. Drinking alcohol in public isn"t allowed. If you decided to feed the birds with the last crumbs (碎屑) of your sandwich, you could be arrested. It"s illegal if you went to a bar for a drink and a cigarette, that would be OK, wouldn"t it? Er... No. You can"t smoke in public in New York City. What"s going on? Why is the city that used to be so open-minded becoming like this? The mayor of New York is behind it all. He has brought in a whole lot of new laws to stop citizens from doing what they want, when they want. The press is shocked. Even the New York police have joined the argument. They recently spent $100,000 on a "Don"t blame the cop" campaign. One New York police officer said, "We raise money for the city by giving people fines for breaking some very stupid laws. It"s all about money." The result is a lot of fines for minor offences. Yoav Kashida, an Israel tourist, fell asleep on the subway. When he woke up, two police officers fined him because he had fallen asleep on two seats (you mustn"t use two seats in the subway). Elle and Serge Schroitman were fined for blocking a driveway with their car. It was their own driveway. The angry editor of Vanity Fair magazine, Graydon Carter, says, "Under New York City law it is acceptable to keep a gun in your place of work, but not an empty ashtray." He should know. The police came to his office and took away his ashtray (烟灰缸). But not all of the New York"s inhabitants are complaining. Marcia Dugatty, 72, said, "The city has changed for the better. If more cities had these laws, America would be a better place to live." Nixon Patricks, 38, a barman, said, "I like the new laws, if people smoked in here, we"d go home smelling of cigarettes." Recent figures show that New York now has fewer crimes per 100,000 people than 193 other US cities. And it"s true—it"s safe, cleaner and more healthy than before. But let"s be honest who goes to New York for its clean streets?
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