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Space is filled with radiant energy and beyond earth’s atmosphere this energy flow steadily and intensely from the sun. An abundant and essential (67) of energy would be used in space by developing satellite solar (68) stations. To live in space, humans must be protected (69) the fierce intensity and penetrating sunlight. The colony will have to have enough energy to (70) a fairly uniform temperature. The sun is not dimmed (71) an atmosphere. Shaded materials not (72) to direct sunlight will almost be absolute zero, while the temperature can soar above the (73) point. The colony will need to have both heaters and (74) Fortunately, sun’s energy can be converted (75) electricity. Converting sun’s energy, we would (76) stations in the space that would intercept (77) sunlight. The stations intercept enough sunlight to (78) five nuclear reactors and they could be as (79) as nine miles long and four miles wide while they weigh twenty thousand tons. This is a (80) free way to generate electricity and cost no (81) than coal or nuclear energy. Solar cells do the actual converting. A useful material found in lunar soil is silicon which is used to make solar cells. (82) we can produce a large amount of these cells and then we avoid any problems of (83) the material from earth. A solar cell is made from two thin layers of silicon. Sunlight (84) on the cell shakes the electrons (85) , and then these electrons move off into an outside circuit, which is detected as an electrical current. Things are arranged (86) most of the work involved in generating the electricity is done by forces associated with the atoms themselves.
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Reality television is a kind of television programming which, it is claimed, presents unscripted dramatic or humorous situations, documents actual events, and features ordinary people rather than professional actors. It could be described as a form of artificial or heightened documentary. Although it has existed in some form or another since the early years of television, the current explosion of popularity dates from around 2000. Reality television covers a wide range of television programming formats, from game or quiz shows which resemble the crazy, often demeaning (贬低人的) programs produced in Japan in the 1980s and 1990s, to monitor focused productions such as Big Brother. Critics say that the term "reality television" is somewhat of a misnomer (误称) and that such shows frequently portray a modified and highly influenced form of reality, with participants put in special locations or abnormal situations, sometimes coached to act in certain ways by off-screen handlers, and with events on screen manipulated through editing and other post-production techniques. Part of reality television’s appeal is due to its ability to place ordinary people in extraordinary situations. For example, on the ABC show, The Bachelor, a male dates a dozen women at the same time, traveling on extraordinary dates to scenic places. Reality television also has the potential to turn its participants into national celebrities, outwardly in talent and performance programs such as Pop Idol, though frequently Survivor and Big Brother participants also reach some degree of celebrity. Some critics have said that the name "reality television" is an inaccurate description for several styles of program included in the kind. In competition-based programs such as Big Brother and Survivor, and other special-living-environment shows like The Real World, the producers design the format of the show and control the day-to-day activities and the environment, creating a completely fabricated(杜撰的) world in which the competition plays out. Producers specifically select the participants, and use carefully designed plots, challenges, events, and settings to encourage particular behaviors and conflicts. Mark Burnett, creator of Survivor and other reality shows, has agreed with this assessment, and avoids the word "reality" to describe his shows; he has said, "I tell good stories. It really is not reality TV. It really is unscripted drama.\ The term "reality television" is inaccurate ______.
How Exercise Makes You Smarter Exercise does more than build muscles and help prevent heart disease. New science shows that it also boosts brainpower--and may offer hope in the battle against Alzheimer(痴呆症). The stereotype of the "dumb jock" has never sounded right to Charles Hillman. A jock himself, he plays hockey four times a week, but when he isn’t body-checking his opponents on the ice, he’s giving his mind a comparable workout in his neuroscience and kinesiology lab at the University of Illinois. Recently he started wondering if there was a vital and overlooked link between brawn and brains--if long hours at the gym could somehow build up not just muscles, but minds. With colleagues, he started an experiment. He rounded up 259 Illinois third and fifth graders, measured their body-mass index and put them through classic PE routines: the "sit-and-reach", a brisk run and timed push-ups and sit-ups. Then he checked their physical abilities against their math and reading scores on a statewide standardized test. Sure enough, on the whole, the kids with the fittest bodies were the ones with the fittest brains, even when factors such as socioeconomic status were taken into account. Sports, Hillman concluded, might indeed be boosting the students’ intellect. Hillman’s study, which will be published later this year, isn’t definitive enough to stand alone. But it doesn’t have to: it is part of a recent and rapidly growing movement in science showing that exercise can make people smarter. Other scientists have found that vigorous exercise can cause nerve cells to form dense, interconnected webs that make the brain run faster and more efficiently. And there are clues that physical activity can stay away from the beginnings of Alzheimer’s disease, ADHD and other cognitive disorders. No matter your age, it seems, a strong, active body is crucial for building a strong, active mind. Some scientists have always suspected as much, although they have not been able to prove it. Now, however, armed with brain-scanning tools and a sophisticated understanding of biochemistry, researchers are realizing that the mental effects of exercise are far more profound and complex processes than they once thought. The processes start in the muscles. When the exercise is available, the muscle sends out chemicals, including a protein called IGF-1 that travels through the bloodstream, across the blood-brain barrier and into the brain itself. And then the brain issues orders fuels almost all the activities that lead to higher thought. With regular exercise, the body builds up its levels of BDNF, and the brain’s nerve cells start to branch out, join together and communicate with each other in new ways. This is the process that underlies learning: every change in the junctions between brain cells signifies a new fact or skill that’s been picked up for future use. BDNF makes that process possible. Brains with more of it have a greater capacity for knowledge. On the other hand, says UCLA neuroscientist Fernando G6mez-Pinilla, a brain that’s low on BDNF shuts itself off to new information. Most people maintain fairly constant levels of BDNF in adulthood. But as they age, their individual neurons (神经)slowly start to die off. Until the mid-90s, scientists thought the loss was permanent-that the brain couldn’t make new nerve cells to replace the dead ones. But animal studies over the last decade have overturned that assumption, showing that "neurogenesis" (神经发生)in some parts of the brain can be induced easily with exercise. Last week’s study, published in the Proceedings of the National Academy of Sciences, extended that principle to humans for the first time. After working out for three months, all the subjects appeared to regain new neurons. This, too, might be BDNF at work, transforming stem cells into full-grown, functional neurons. "It was extremely exciting to see this exercise effect in humans for the first time," says Scott Small, a Columbia University Medical Center neurologist who coauthored the study with Salk Institute neurobiologist Fred Gage. "In terms of trying to understand what it means, the field is just exploding." As far as scientists know, the new neurons created by exercise are produced in only one place: the dentate gyrus, an area that controls learning and memory. This region helps the brain match names to faces--one of the first skills to erode as we age. New neurons can’t grow throughout the rest of the brain. But other regions benefit from exercise in many secondary ways. Blood volume, like brain volume, increases with exercise. Active adults have less inflammation in the brain. They also have fewer "little possibility of strokes that can impair cognition without the person even knowing," says Kristine Yaffe, a neuroscientist from University of California. Still other researchers have found that athletes have more cells that support neurons and increase neurotransmitters after they’re used to send messages from cell to cell. And even the levels of those neurotransmitters are higher in people who exercise frequently. Unlike neurogenesis, which can take weeks to occur, most of these additional effects appear almost immediately. Get off the treadmill (踩单车) after a half-hour workout, says Hillman, and "within 48 minutes" your brain will be in better shape. But alas, these benefits are somewhat transient(短暂的). Like weight, mental fitness has to be maintained. New neurons, and the connections between them, will stick around for years, but within a month of inactivity, "it will shrink down, and then the neurons don’t function as well anymore," says William Greenough, a psychologist at the University of Illinois. Let your body go, then, and your brain will follow. To keep the effects, you’ve got to keep working out. "If you’re thinking that by exercising at age 20 you’re going to have some effect on what you’re like at age 70," Greenough adds, you’d better be willing to commit to 50 years of hitting the gym. Unless, that is, you’re a kid. Most studies of exercise and cognition have focused on older people--the folks who are just starting to worry that their minds aren’t what they used to be--but the effects of physical exertion on the brain aren’t limited to that group at all. In fact, in young children, they’re even more potent. Exercise probably has "a more long-lasting effect on brains that are still developing," says Phil Tomporowski, a professor of exercise science at the University of Georgia. In kids, as in adults, the brain reaps many benefits from exercise. This won’t surprise parents of kids with ADHD, many of whom already use physical activity as a substitute or supplement for drugs. Those animals studies have shown that the "neurogenesis" in some parts of the brain can be regained by ______.
Space is filled with radiant energy and beyond earth’s atmosphere this energy flow steadily and intensely from the sun. An abundant and essential (67) of energy would be used in space by developing satellite solar (68) stations. To live in space, humans must be protected (69) the fierce intensity and penetrating sunlight. The colony will have to have enough energy to (70) a fairly uniform temperature. The sun is not dimmed (71) an atmosphere. Shaded materials not (72) to direct sunlight will almost be absolute zero, while the temperature can soar above the (73) point. The colony will need to have both heaters and (74) Fortunately, sun’s energy can be converted (75) electricity. Converting sun’s energy, we would (76) stations in the space that would intercept (77) sunlight. The stations intercept enough sunlight to (78) five nuclear reactors and they could be as (79) as nine miles long and four miles wide while they weigh twenty thousand tons. This is a (80) free way to generate electricity and cost no (81) than coal or nuclear energy. Solar cells do the actual converting. A useful material found in lunar soil is silicon which is used to make solar cells. (82) we can produce a large amount of these cells and then we avoid any problems of (83) the material from earth. A solar cell is made from two thin layers of silicon. Sunlight (84) on the cell shakes the electrons (85) , and then these electrons move off into an outside circuit, which is detected as an electrical current. Things are arranged (86) most of the work involved in generating the electricity is done by forces associated with the atoms themselves.
The oceans, which cover nearly three-quarters of Earth’s surface, remain largely unexplored because of their vastness and inaccessibility to us air breathers. Webb Research of East Falmouth, Massachusetts, hopes to open up much of that mystery field with a new underwater vehicle that is pushed ahead solely by the ocean itself, so it can potentially study the watery depths for years at a time. Such long-lasting detectors may someday form fleets that provide up-to-minute data for weather forecasting. In the past, such autonomous underwater vehicles, or AUVs, have been battery powered and therefore required frequent recharges that limited their distance and depth of travel. Webb’s Slocum glider(滑翔机) hopes to solve this problem. "We conceived of a thermally powered engine to get the energy from the colder deep water of the ocean and the shallower warm water," Clayton Jones, an engineer at Webb Research, explains. "We picked out a material that undergoes a state change between those two temperatures in the ocean." When cold, this form-shifting substance is a compact solid. When warm, it expands and becomes a less dense liquid. The material’s expansion in warmer waters charges an internal mechanism that acts like stored power to control its buoyancy: by pumping mineral oil in and out of an external air bag, it alters its volume but maintains its weight. "The glider takes up more volume and becomes lighter than the water around it--less dense," Jones says. Scientists can also fit the Slocum glider with a variety of different sensory equipment and Global Positioning Systems. Each time it surfaces, it can raise its tail antenna(天线) to transmit data to and receive instructions from researchers sitting comfortably in their cozy offices. The glider will have its first test in salt water at the end of this September. The gliders could also get through and follow previously unstudied phenomena such as small underwater eddies (漩涡), which are vital to understanding water transport and heat flow in the ocean and therefore play an important role in storm formation and other weather development. "We have all these data snapshots(快照) from floats that just flow with the deep ocean current," Jones says. "To be able to fly through eddy sections, then transport with the whole eddy itself as it moves through the ocean, would be a very nice phenomenon to take a look at.\ Which of the following is true about the newly-designed AUV
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