单选题The central plan, ______ by the government, shows the amount of each goods produced by the various firms and shared among different households for consumption.

单选题She ______ the list of names to see if hers was on it.

单选题I took ______ of the opportunity to tell him what I thought.

单选题The ship's generator broke down, and the pumps had to be operated ______ instead of mechanically.

单选题He became aware that he had lost his audience since he had not been able to talk ______ around one topic.

单选题Most people who develop Lyme disease, a tick-born infection that's endemic in parts of the Northeast and Midwest, are easily cured by taking an antibiotic like doxycycline for a couple of weeks. But for years a debate has raged over what to do about patients whose symptoms (fatigue, mental confusion, joint pain) never seem to clear up. One small but vocal group of doctors and patient advocates believes that Lyme's corkscrew-shaped spirochetes have tunneled deep into their victims' bodies and can be eradicated only with intensive antibiotic treatment over many months. Another group believes, just as adamantly, that the bacteria are long gone, making further treatment with powerful antibiotics-- which can lead to potentially fatal infections or blood clots--positively dangerous. Now comes word of two studies in the New England Journal of Medicine that show that long-term antibiotic treatment is no better than a placebo for folks with chronic Lyme disease. Originally scheduled for publication in July, the research is part of a group of findings made public last week--just in time for the peak Lyme months of June and July. If confirmed by another major study that's looking at chronic Lyme and antibiotics from a slightly different perspective, the results would seem to settle the question once and for all. Researchers from Boston, New Haven, Conn., and Valhalla, N.Y., followed 129 patients who had previously been treated for well-documented cases of Lyme disease. Sixty-four were given antibiotics directly into their veins for a month, followed by two months of oral antibiotics. The others received dummy medications. A third of the chronic Lyme patients got better while taking the antibiotics. But so did a third of those on the placebo. Indeed, the results were so similar that a monitoring board decided to cut the trials short rather than add more subjects to the test groups. Unfortunately, the debate over chronic Lyme has become so heated that no one expects the controversy to go away. But both sides may take comfort in the other findings that were released by the New England Journal last week. After studying 482 subjects bitten by deer ticks in a part of New York with a lot of Lyme disease, researchers concluded that a singly 200-mg dose of doxycycline dramatically cut the risk of contracting the disease. That good news is tempered somewhat by the fact that 80% of patients who develop the infection don't remember ever being bitten by a tick. (The bugs inject an anesthetic into the skin to mask the pain and in their nymph stage are so small--about the size of a poppy seed--that they are easily overlooked. ) There's still plenty you can do to protect yourself in a Lyme-infested neighborhood: tuck your pants in your socks, spray DEET on your clothing, check yourself and your kids for ticks. And if you develop a spreading red rash--particularly if it's accompanied by joint pain, chills or confusion--make sure you see a doctor right away. The trick, as always, is to be vigilant without overreacting.

单选题Engineering students are supposed to be examples of practicality and rationality, but when it comes to my college education, I am an idealist and a fool. In high school I wanted to be an electrical engineer and, of course, any sensible student with my aims would have chosen a college with a large engineering department, famous reputation and lot of good labs and research equipment. But that's not what I did. I chose to study engineering at a small liberal-arts university that doesn't even offer a major in electrical engineering. Obviously, this was not a practical choice; I came here for more noble reasons. I wanted a broad education that would provide me with flexibility and a value system to guide me in my career. I wanted to open my eyes and expand my vision by interacting with people who weren't studying science or engineering. My parents, teachers and other adults praised me for such a sensible choice. They told me I was wise and mature beyond my 18 years, and I believed them. I headed off to college, feeling sure I was going to have an advantage over those students who went to big engineering "factories" where they didn't care if you had values or were flexible. I was going to be a complete engineer: technical genius and sensitive humanist all in one. Now I'm not so sure. Somewhere along the way my noble ideals crashed into reality, as all noble ideals eventually do. After three years of struggling to balance math, physics and engineering courses with liberal arts courses, I have learned there are reasons why few engineering students try to reconcile engineering with liberal arts courses in college. The reality that has blocked my path to become the typical successful student is that engineering and the liberal arts simply don't mix as easily as I assumed in high school. Individually they shape a person in very different ways; together they threaten to confuse. The struggle to reconcile the two fields of study is difficult.

单选题But by the time we are adult, the childhood hiding which dwindled to adolescent shyness, is expected to disappear altogether, as we bravely stride out to meet our guests, hosts, companions, relatives, colleagues, customers, clients, or friends.

单选题The customs officer asked me if I had anything to ______

单选题The old woman is chronically ill in bed and seldom goes out.

单选题There are______differences between theory and practice.(2010年北京航空航天大学考博试题)

单选题{{B}}Passage 4{{/B}} For years pediatricians didn't worry much about treating hypertension in their patients. After all, kids grow so fast, it's hard keeping up with their shoe size, let alone their blood pressure. Sure, hypertension in adults places them at greater risk of heart, attack and stroke. But nobody likes the idea of starting youngsters on blood-pressure medicine they could wind up taking the rest of their lives. Who knows what previously unheard-of side effects could crop up after five or six decades of daily use? The rationale has been: kids grow out of so many things, maybe they'll grow out of this too. Now, though, comes word that high blood pressure can be destructive even in childhood. According to a recent report in the journal Circulation, 19of 130children with high blood pressure developed a dangerous thickening of the heart muscle that, in adults at least, has been linked to heart failure. "No one knows if this pattern holds true for younger patients as well," says Dr. Stephen Daniels, a pediatric cardiologist who led the study at Children's Hospital Medical Center in Cincinnati, Ohio. "But it's worrisome." Who's most at risk? Boys more man girls, expecially boys who are overweight. Their heart works so hard to force blood through extra layers of fat that its walls grow more dense. Then, after decades of straining, it grows too big to pump blood very well. Fortunately the abnormal, thickering can be spotted by ultrasound. And in most case, getting that blood pressure under control--through weight loss and exercise or, as a last resort, drug treatment--allows the overworked muscle to shrink to normal size. How can you tell if yours are like the 670, 000 American children ages 10 to 18 with high blood pressure? {{B}}It's not the sort of thing you can catch by putting your child's arm in a cuff at the free monitoring station in your local grocery.{{/B}} You should have a test done by a doctor, who will consult special tables that indicate me normal range of blood pressure for a particular child's age, height and sex. If the doctor finds an abnormal result he will repeat the test over a period of months to make sure the reading isn't a fake. He'll also check, whether other conditions, like kidney disease, could be the source of the trouble. Because hypertension can be hard to detect the National Heart. Lung and Blood Institute recommends annual blood-pressure checks for every child over age 3. About half the eases of hypertension stem directly from kids being overweight. And the problem is likely to grow. Over the past 30 years the proportion of children in the U. S. who are overweight has doubled, from 5% to 11% or4.7 million kids. You can keep your children from joining their ranks by clearing the junk food from your pantry and honking your kids--the earlier the better--on healthy, attractive snacks like fruits (try freezing some grapes/or carrot sticks with salsa. Not only will they lower your children's blood pressure: these foods will also boost their immune system and unclog their plumbing. Meanwhile, make sure your kids spend more time on the playground than with their PlayStation. Even if they don't shed a pound, vigorous exercise will help keep their blood vessels nice and wide, lowering their blood pressure. And of course, they'll be more likely to eat light and exercise if you set a good example.

单选题As one works with color in a practical or experimental way, one is impressed by two apparently unrelated facts. Color as seen is a mobile changeable thing depending to a large extent on the relationship of the color to other colors seen simultaneously. It is not fixed in its relation to the direct stimulus which creates it. On the other hand, the properties of surfaces that give rise to color do not seem to change greatly under a wide variety of illumination colors, usually (but not always) looking much the same in artificial light as in daylight. Both of these effects seem to be due in large part to the mechanism of color adaptation mentioned earlier. When the eye is fixed on a colored area, there is an immediate readjustment of the sensitivity of the eye to color in and around the area viewed. This readjustment does not immediately affect the color seen but usually does affect the next area to which the gaze is shifted. The longer the time of viewing, the higher the intensity, and the larger the area, the greater the effect will be in terms of its persistence in the succeeding viewing situation. As indicated by the work of Wright and Shouted, it appears that, at least for a first approximation, full adaptation takes place over a very brief time if the adapting source is moderately bright and the eye has been in relative darkness just previously. As the stimulus is allowed to act, however, the effect becomes more persistent in the sense that it takes the eye longer to regain its sensitivity to lower intensities. The net result is that, if the eye is so exposed and then the gaze is transferred to an area of lower intensity, the loss of sensitivity produced by the first area will still be present and appear as an "afterimage" superimposed on the second. The effect not only is present over the actual area causing the "local adaptation" but also spreads with decreasing strength to adjoining areas of the eye to produce "lateral adaptation." Also, because of the persistence of the effect if the eye is shifted around from one object to another, all of which are at similar brightness or have similar colors, the adaptation will tend to become uniform over the whole eye.

单选题Nanotechnology, according to its fans, will jump-start a new industrial revolution with molecular-sized structures as complex as the human cell and 100 times stronger than steel. The new technology transforms everyday products and the way they are made by manipulating atoms so that materials can be shrunk, strengthened and lightened all at once. To date only modest nanotech-based products—such as stain-resistant fabrics and fresh food packaging—have entered the market, but some scientists predict nanotechnology will eventually be the only game in town. "It will be a ubiquitous technology," said George Stephanopoulos, professor of chemical engineering at the Massachusetts Institute of Technology. He echoes other nanotech supporters who say industrial countries are already sliding toward its use in every aspect of manufacturing. Aided by recent advances in microscopes, scientists can now place single atoms where they want for the first time. The potential applications are numerous, with microscopic computers, cancer-killing antennae and nonpolluting car engines on the distant horizon. When it's all going to happen, though, is another matter. According to most scientific accounts, the nanotech future may be 10 to 20 years off. Major hurdles need to be jumped. First, there is a lack of economic mass production. Some of the more complicated devices would require exact placement of billions of atoms. "It may take the lifetime of the universe to complete the construction of (such a) device," said George Barbastathis, assistant professor at MIT. Another challenge is bridging the nanoscale and macroscopic, he said. In other words, the smallness of a nano device is useless when it must be attached to large wires. It's unclear how scientists will overcome these problems. And fears derived from science fiction threaten to derail nanotechnology even as it emerges, in much the same way popular anxiety over "super-weeds" and "frankenfoods" have hobbled biotechnology in agriculture and fear of "designer babies" has set back stem-cell research. Lured by a market with billions of dollars in potential profits, giants like GE, Intel, Motorola and IBM are already heavily involved in research. Worldwide, the two industries with the potential to win big with nanotechnology are electronics and biotechnology, according to MIT researchers. On the biotech front, scientists are promoting the notion of nanoparticles made from gold that could be triggered remotely to heat and kill individual cancer cells. Nanotechnology holds equal promise for wealth creation, hut there isn't a consensus among venture capitalists on how to realize it. "Which direction is it going to work out in? That's the question on everyone's mind," Gang Chen, an associate professor at the MIT, told scientists at a Boston nano gathering.

单选题The company used so much coal that it has a train to______the delivery process. (2004年上海理工大学考博试题)

单选题Building this road will ______ the construction of ten bridges, and then the total cost reaches 1 million US dollars. A. evolve B. involve C. revolve D. devolve

单选题As online computer systems become more popular, televisions and computers are increasingly______. Such technologies combine the capabilities of computers, television etc, and greatly expand the services that can be provided.

单选题A young man sees a sunset and, unable to understand or express the emotion that it ______ in him, concludes that it must be the gateway to a world that lies beyond.