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Although many factors affect human health during periods in space, weightlessness is the dominant and single most important one. The direct and indirect effects of weightlessness lead to a series of related responses. Ultimately, the whole body, from bones to brain, kidneys to bowels, reacts.When space travelers grasp the wall of their spacecraft and jerk their bodies back and forth, they say it feels as though they are stationary and the spacecraft is moving. The reason is based in our reliance on gravity to perceive our surroundings.The continuous and universal nature of gravity removes it from our daily notice, but our bodies never forget. Whether we realize it or not, we have evolved a large number of silent, automatic reactions to cope with the constant stress of living in a downward-pulling world. Only when we decrease or increase the effective force of gravity on our bodies do our minds perceive it.Our senses provide accurate information about the location of our center of mass and the relative positions of our body parts. Our brains integrate signals from our eyes and ears with other information from the organs in our inner ear, from our muscles and joints, and from our senses of touch and pressure.The apparatus of the inner ear is partitioned into two distinct components: circular, fluid-filled tubes that sense the angle of the head, and two bags filled with calcium crystals embedded in a thick fluid, which respond to linear movement. The movement of the calcium crystals sends a signal to the brain to tell us the direction of gravity. This is not the only cue the brain receives. Nerves in the muscles, joints, and skin—particularly the slain on the bottom of the feet—respond to the weight of limb segments and other body parts.Removing gravity transforms these signals. The inner ear no longer perceives a downward tendency when the head moves. The limbs no longer have weight, so muscles are no longer required to contract and relax in the usual way to maintain posture and bring about movement. Nerves that respond to touch and pressure in the feet and ankles no longer signal the direction of down. These and other changes contribute to orientation illusions, such as a feeling that the body or the spacecraft spontaneously changes direction. In 1961 a Russian astronaut reported vivid sensations of being upside down; one space shuttle specialist in astronomy said, "When the main engines cut off, I immediately felt as though we had inverted 180 degrees." Such illusions can recur even after some time in space. From the first two paragraphs we learn that weightlessness is caused by （）
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下面的短文后列出了7个句子，请根据短文的内容对每个句子作出判断；如果该句提的是正确信息，请选择A；如果该句提的是错误信息，请选择B；如果该句的信息文中没有提及，请选择C。 Tokyo is World’s Priciest City The weak American dollar and strong European and Asian currencies helped make Tokyo and London the most expensive cities in the world, according to a recent survey. American cities were absent from the top 10, with the most expensive U. S. city, New York, dropping two spots from last year to 12 in the survey of 144 urban areas conducted by Mercer Human Resource Consulting. Moscow ranked in third place, with Osaka, and Hong Kong rounding out the top five most expensive cities. The survey, drawn up twice a year, ranks cost of living for foreign workers, not local residents, and is used primarily by multinational companies to determine pay for expatriate employees. "The euro appreciated (升值) more than 11 percent in the last six months. " said Marie-Laurence Sepede, senior researcher at Mercer. "So that made European cities go up and U.S. cities drop. " Sepede noted that while U.S. cities got cheaper in relation to those in Europe and Asia, the rankings among: American cities remained similar to previous years, with Los Angeles, Chicago and San Francisco all placing high on the list. Also not able was the climb of Australian and New Zealand cities up the list, a shift caused by those nation’s strong currencies. Sydney moved from 67 last year to 20 this year, and Auckland, New Zealand climbed 35 places to 80. The rest of the top 20 remained fairly constant, although Paris, Vienna, Austria and Istanbul, Turkey made their first appearances so high in the rankings. The survey took into consideration 250 criteria, including the cost of utilities, food and entertainment. While the survey looked at a range of living standards, Sepede said the study was most representative of the expenses of people working for big international corporations and maintaining fairly high standards of living. Mercer said the continued appreciation of the euro against the U. S. dollar could eventually force companies to move employees and reorganize. "Mainly, the depreciation(贬值) of the dollar makes it cheaper to send employees to American cities," said Jackie Barber, a spokeswoman for the survey. The survey is a useful reference for multinational companies.
第二篇 Oceanography Oceanography has been defined as "the application of all sciences to the study of the sea. " Before the nineteenth century, scientists with an interest in the sea were few. Certainly Newton considered some theoretical aspects of it in his writings, but he was reluctant to go to sea to farther his work. For most people the sea was remote, and with the exception of early intercontinental (大陆间的 ) travelers or others who earned a living from the sea, there was little reason to ask many questions about it, let alone to ask what lay beneath the surface. The first time that the question-" what is at the bottom of the oceans" had to be answered with any commercial consequence was when the laying of a telegraph cable from Europe to America was proposed. The engineers had to know the depth profile(起伏形状)of the route to estimate the length of cable that had to be manufactured. It was to Maury of the LIS Navy that the Atlantic Telegraph Company turned, in 1853, for information on this matter. In the 1840s, Maury had been responsible for encouraging voyages during which soundings(测水深) were taken to investigate the depths of the North Atlantic and Pacific Oceans. Later, some of his findings aroused much. popular interest in his book "The Physical Geography of the Sea". The cable was laid, but not until 1866 was the connection made permanent and reliable. At the early attempts, the cable failed and when it was taken out for repairing it was found to be covered with living creatures, a fact which defied contemporary scientific opinion that there was no life in the deeper parts of the sea. Within a few years oceanography was under way. In 1872, Thomson led a scientific expedition (考察), which lasted for four years and brought home thousands of samples from the sea. Their classification and analysis occupied scientists for years and led to a five-volume report, the last volume being published in 1895. This passage is mainly about______.
下面的短文有15处空白，请根据短文内容为每处空白白确定1个最佳选项。 It sounds all wrong-drilling holes in a piece of wood to make it more resistant to knock. But it works because the energy from the blow gets distributed throughout the wood rather than focusing on one weak spot. The discovery should lead to more effective and lighter packaging materials. Carpenters have known (51) centuries that some woods are tougher than others. Hickory(山核桃木), for example, was turned into axe handles and cartwheel spokes (车轮辐条) because it can absorb shocks without breaking. White oak (橡木), for example, is much more easily damaged, (52) it is almost as dense. Julian Vincent at Bathe University and his team were convinced the wood’s internal structure could explain the differences. Many trees have tubular(管状的) vessels that run (53) the trunk and carry water to the leaves. In oak they are large, and arranged in narrow bands, but in hickory they are smaller, and more evenly distributed. The researchers (54) this layout might distribute a blow’s energy throughout the wood, soaking up a bigger hit. To test the idea, they drilled holes 0.65 millimeters across into a block of spruce(云杉), a wood with (55) vessels, and found that (56) withstood a harder knock. (57) when there were more than about 30 holes per square centimeter did the wood’s performance drop off. A uniform substance doesn’t cope well with knocks because only a small proportion of the material is actually (58) . All the energy from the blow goes towards breaking the material in one or two places, but often the pieces left (59) are pristine(未经破坏的). "But instead of the energy being concentrated in one place, the holes provide many weak spots that all absorb energy as they break", says Vincent, "You are controlling the places (60) the wood breaks, and it can then absorb more (61) , more safely". The researchers believe the principle could be applied to any material- (62) example, to manufacture lighter and more protective packaging. That could (63) be used in car bumpers (保险杠), crash barriers and armor for military vehicles, says Ulrike Wegst, (64) the Max Plank Institute for Mental Research in Stuttgart. But she emphasizes that you’d (65) to design the substance with the direction of force in mind. "The direction of loading is crucial", she says.
下面的短文有15处空白，请根据短文内容为每处空白白确定1个最佳选项。 It sounds all wrong-drilling holes in a piece of wood to make it more resistant to knock. But it works because the energy from the blow gets distributed throughout the wood rather than focusing on one weak spot. The discovery should lead to more effective and lighter packaging materials. Carpenters have known (51) centuries that some woods are tougher than others. Hickory(山核桃木), for example, was turned into axe handles and cartwheel spokes (车轮辐条) because it can absorb shocks without breaking. White oak (橡木), for example, is much more easily damaged, (52) it is almost as dense. Julian Vincent at Bathe University and his team were convinced the wood’s internal structure could explain the differences. Many trees have tubular(管状的) vessels that run (53) the trunk and carry water to the leaves. In oak they are large, and arranged in narrow bands, but in hickory they are smaller, and more evenly distributed. The researchers (54) this layout might distribute a blow’s energy throughout the wood, soaking up a bigger hit. To test the idea, they drilled holes 0.65 millimeters across into a block of spruce(云杉), a wood with (55) vessels, and found that (56) withstood a harder knock. (57) when there were more than about 30 holes per square centimeter did the wood’s performance drop off. A uniform substance doesn’t cope well with knocks because only a small proportion of the material is actually (58) . All the energy from the blow goes towards breaking the material in one or two places, but often the pieces left (59) are pristine(未经破坏的). "But instead of the energy being concentrated in one place, the holes provide many weak spots that all absorb energy as they break", says Vincent, "You are controlling the places (60) the wood breaks, and it can then absorb more (61) , more safely". The researchers believe the principle could be applied to any material- (62) example, to manufacture lighter and more protective packaging. That could (63) be used in car bumpers (保险杠), crash barriers and armor for military vehicles, says Ulrike Wegst, (64) the Max Plank Institute for Mental Research in Stuttgart. But she emphasizes that you’d (65) to design the substance with the direction of force in mind. "The direction of loading is crucial", she says.
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