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A type of cell that floats freely in the amniotic fluid of pregnant women has been found to have many of the same traits as embryonic stem cells, including an ability to grow into brain, muscle and other tissues that could be used to treat a variety of diseases, scientists reported yesterday.The cells, shed by the developing fetus and easily retrieved during routine prenatal testing, are easier to maintain in laboratory dishes than embryonic stem cells-the highly versatile cells that come from destroyed human embryos and are at the center of a heated congressional debate that will resume this week.Moreover, because the cells are a genetic match to the developing fetus, tissues grown from them in the laboratory will not be rejected if they are used to treat birth defects in that newborn, researchers said. Alternatively, the cells could be frozen, providing a personalized tissue bank for use later in life.The new cells are adding credence to an emerging consensus among experts that the popular distinction between embryonic and “adult” stem cells-those isolated from adult bone marrow and other organs-is artificial.Increasingly, it appears there is a continuum of stem cell types, ranging from the embryonic ones that can morph into virtually any kind of tissue but are difficult to tame, up to adult ones that can turn into a limited number of tissues but are relatively easy to control.The newly analyzed fetal stem cells, scientists said, have many of the advantages of both.“They grow fast, as fast as embryonic stem cells, and they show great pluripotentiality,” meaning they can become many kinds of tissues, said study leader Anthony Atala, director of the Institute for Regenerative Medicine at Wake Forest University School of Medicine in Winston-Salem, N.C. “But they remain stable for years without forming tumors,” he added, something that embryonic cells are not very good at.Atala and other scientists emphasized that they don’t believe the cells will make embryonic stem cells irrelevant.“There’s not going to be one shoe that fits all,” said Robert Lanza, scientific director at Advanced Cell Technology in Worcester, Mass. “We’re going to have to see which ones are most useful for which clinical conditions.”George Daley, a Harvard stem cell researcher, echoed that sentiment. “They are not a replacement for embryonic stem cells,” he said.But in the past, even hints that non-embryonic cells might have medical potential similar to embryonic ones have complicated the political push to expand federal funding for the controversial field. And accordingly, opponents quickly pounced on the new results.65.( )is not a trait of embryonic stem cells.66. The cells that are shed by the developing fetus are( ).67. Tissues grown from these cells in the laboratory will not be rejected as they are( ).68. Embryonic stem cells can( ).69. Robert Lanza said “There’s not going to be one shoe that fits all.” He meant( ).70. The word “retrieved” in the second paragraph can be best replaced by( ).

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Perhaps the real virtue of the UglyRipe’s “ugliness,” which is nothing compared with the deformed beauty of true heirloom tomatoes, is that it helps us see how strange the uniformity of regular winter tomatoes really is. For a backyard grower, taste is everything. But in commercial production, taste is an abstraction. It is what’s left after all the other criteria for a good commercial tomato have been met: disease resistance, regular shape, consistent ripening, the ability to withstand picking and packing and shipping, a long shelf life. Taste is too subjective, according to the Florida Tomato Committee, to judge tomatoes by.The UglyRipe may be a better tomato. After all, its growers have selected for better taste, not perfect shape. But one thing that would certainly make the UglyRipe a better tomato is a different way of growing it. Santa Sweets produces organic UglyRipes, but they are few and hard to find. It now grows its conventional tomatoes without using agricultural chemicals that carry reproductive risks—but it still uses methyl bromide, a powerful, ozone---depleting pesticide, to fumigate the soil in which conventional UglyRipes grow. Under the terms of the Montreal Protocol, the use of methyl bromide was supposed to be phased out completely by January 2005. But for the past few years, the Bush administration has claimed an exemption for “critical uses,” one of which is growing winter tomatoes in Florida. We used to consider it a luxury to eat fruits and vegetables out of season. But what we eat out of season has been machined to withstand the rigors of the supply chain and produced in ways that only our ignorance can sustain. The truth is that there is no luxury---nor critical use—in it. Even an ugly, better-tasting winter tomato isn’t worth the price. 59. The word “machined” in the last paragraph means( ).60. The criteria for a good commercial tomato does not include( ).61.( )makes the UglyRipe better.62. Methyl bromide is used to( ).63. Methyl bromide, a powerful ozone-depleting pesticide( ).64. The main point of this article is( ).

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A finalist in a youth oratorical contest, Cecile’s speech focuses on a history of Americans and the world turning their backs on injustice, losing sight of “our humanitarian obligation.” The unconscionable acts of history are repeating, but the world is “bickering over the terminology that is used to describe what Darfur is facing,” she said, with a swing of her hip and an indignant glare.How could the United States that bonded after Sept. 11, 2001, leave people on rooftops surrounded by floodwaters almost four years later, she questioned. It all comes down to “people neglecting people, ” she said matter-of-factly.“Everybody is part of God’s creation. Everybody deserves help. We all are going to need it eventually in our lifetime, and for us to neglect anyone from anywhere is just horrible,” Cecile said, shaking her head.Emoni draws parallels between the Holocaust and current events in Africa by citing a lack of guidance, understanding and compassion.“How can we say hope for those unseen when we do not help them have hope or believe there is hope because we can’t see them?” the Godwin Middle School student asked, nearly making the walls shake with her emphasis on the word “we”.The world has a history of great leaders who brought international wrongs to light, she said, jabbing her index finger into the air in front of her. The situation in Darfur has primarily been ignored because the world lacks a powerful leader to get that message out, she said, furiously pacing the classroom floor.“I think if people learn about it and they hear about it…if they understood it, then we can make a difference,” Emoni said, getting to the heart of her argument.All three students understand it could be their voice that motivates the masses tomorrow. Their speeches could bring the issues into the light as they follow the tradition of great orators before them on the day honoring one of the greatest.After careful, quiet consideration, Seth said the contest and celebration would have moved King.“It is the little people trying to make a difference, reciting speeches and all of this. He can feel happy that his work, like, what he left behind, is still going on as if he was here today,” he said.“And how did he start it? He started it through his voice, you know. Through just speaking up for what is right. And not being afraid of what people think of you, but knowing what is right and setting aside all other things,” an excited and boisterous Cecile said.53. The word “boisterous” in the last paragraph can be substituted by( ).54. In her speech, Cecile, a finalist in a youth oratorical contest accuses America of( ).55. Emoni, another contestant, compared the Holocaust to current events in Africa by not citing( ).56. Emoni said the world lacks( ).57. Emoni’s main points did not include( ).58. Seth, another contestant, said if Dr. Martin Luther King, Jr. were there, he would( ).

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Severe drought in the 1970s and 80’s, coupled with a population explosion and destructive farming and livestock practices, was denuding vast swaths of land. The desert seemed determined to swallow everything. So Mr. Danjimo and other farmers in Guidan Bakoye,the Sahel, a semiarid belt that spans Africa just below the Sahara took a small but radical step. No longer would they clear the saplings from their fields before planting, as they had for generations. Instead they would protect and nurture them, carefully plowing around them when sowing millet, sorghum, peanuts and beans. Today, the success in growing new trees suggests that the harm to much of the Sahel may not have been permanent, but a temporary loss of fertility. The evidence, scientists say, demonstrates how relatively small changes in human behavior can transform the regional ecology, restoring its biodiversity and productivity. In Niger’s case, farmers began protecting trees just as rainfall levels began to rise again after the droughts in the 1970s and 80’s. Another change was the way trees were regarded by law. From colonial times, all trees in Niger had been regarded as the property of the state, which gave farmers little incentive to protect them. Trees were chopped for firewood or construction without regard to the environmental costs. Government foresters were supposed to make sure the trees were properly managed, but there were not enough of them to police a country nearly twice the size of Texas. But over time, farmers began to regard the trees in their fields as their property, and in recent years the government has recognized the benefits of that outlook by allowing individuals to own trees. Farmers make money from the trees by selling branches, pods, fruit and bark. Because those sales are more lucrative over time than simply chopping down the tree for firewood, the farmers preserve them. The greening began in the mid-1980s, Dr. Reij said, “and every time we went back to Niger, the scale increased.” “The density is so spectacular.” he said. Mahamane Larwanou, a forestry expert at the University of Niamey in Niger’s capital, said the regrowth of trees had transformed rural life in Niger. “The benefits are so many it is really astonishing,” Dr. Larwanou said. “The farmers can sell the branches for money. They can feed the pods as fodder to their animals. They can sell or eat the leaves. They can sell and eat the fruits. Trees are so valuable to farmers, so they protect them.” They also have extraordinary ecological benefits. Their roots fix the soil in place, preventing it from being carried off with the fierce Sahelian winds and preserving arable land. The roots also help hold water in the ground, rather than letting it run off across rocky, barren fields into gullies where it floods villages and destroys crops. One tree in particular, the Faidherbia albida, known locally as the gao tree, is particularly essential. It is a nitrogen-fixing tree, which helps fertilize the soil. Its leaves fall off during the rainy season, which means it does not compete with crops for water, sun or nutrients during the growing period. The leaves themselves become organic fertilizer when they fall. 47. The word “arable” in the third paragraph from the bottom can be substituted by( ).48. The denuding of vast swaths of land was not caused by( ).49. A small change in human behavior can( ).50. Today the law has changed to( ).51. The benefits of trees to farmers does not include( ).52.( )is not an ecological benefit of the trees in rural Niger.

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A Washington-based think tank has been soliciting critiques of the just-released international assessment of the evidence on climate change, a move that prompted some academics and environmentalists to accuse the group of seeking to distort the latest evidence for global warming.Advocacy groups such as Greenpeace and the Public Interest Research Group questioned why the American Enterprise Institute (AEI) has offered $10,000 to academics willing to contribute to a book on climate—change policy, an overture that was first reported Friday in London’s Guardian newspaper.Greenpeace spokeswoman Jane Kochersperger, who noted that AEI has received funding from Exxon Mobil in recent years, said yesterday that the think tank “has clearly hit a new low … when it’s throwing out cash awards under the rubric of ‘reason’ to create confusion on the status of climate science. Americans are still suffering the impacts of Hurricane Katrina, and it’s clearly time for policymakers on both sides of the aisle to take substantive action on global warming and ignore Exxon Mobil’s disinformation campaign via climate skeptics.”AEI visiting scholar Kenneth Green—one of two researchers who has sought to commission the critiques—said in an interview that his group is examining the policy debate on global warming, not the science.“It’s completely policy-oriented,” said Green, adding that a third of the academics AEI solicited for the project are interested in participating. “Somebody wants to distort this.”In July 2006, Green and AEI resident scholar Steven F. Hayward —both of whom have questioned the need for caps on emissions of carbon dioxide and other gasses linked to global warming —started soliciting essays from academics on the then-upcoming report on global warming by the U.N. —sponsored Intergovernmental Panel on Climate Change (IPCC). The survey’s authors, who hail from more than 100 countries, said in their report Friday that they are at least 90 percent certain that human activity accounted for climate change over the past 50 years.“The purpose of the project is to highlight the strengths and weaknesses of the IPCC process, especially as it bears on policy responses to climate change,” the two men wrote. “As with any large-scale ‘consensus’ process, the IPCC is susceptible to self-selection bias in its personnel, resistant to reasonable criticism and dissent, and likely to have summary conclusions that are poorly supported by the analytical work of the complete Working Group reports.”At least two academics — Texas A&M University atmospheric sciences professor Gerald North and Texas A&M climate researcher Steven Schroeder — turned down AEI’s offer because they feared their work would be politicized.Schroeder, who has worked with Green in the past and has questioned some aspects of traditional climate modeling, said in an interview that he did not think AEI would have skewed his results. But he added that he worried his contribution might have been published alongside “off-the-wall ideas” questioning the existence of global warming.“We worried our work could be misused even if we produced a reasonable report,” Schroeder said. “While any human endeavor can be criticized, the IPCC system greatly exceeds the cooperation, openness and scientific rigorousness of the process applied to any other problem area that has significant effects on society.”41. The word “commission” in the fourth paragraph can be best replaced by( ).42. Some academics and environmentalists accuse( )of seeking to distort the latest evidence of global warming.43. Advocacy groups include( ).44. Jane Kochersperger is( ).45. Kenneth Green believes( ).46. The best title for this article is( ).

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