任务型阅读

任务型阅读一Do you often see silly words or drawing scratched onto the desks in your classroom? Have you ever found chewing gum on the floor of your classroom or around the campus? How many times have you seen broken windows、doors in the classrooms and school buildings? This is vandalism, the destruction or damaging of public property for no obvious reason.Vandalism in school is becoming a growing problem, and it is costing us more than money. It is expensive to repaint the desks, clear them of chewing gum and to repair school furniture. Moreover, it costs us our sense of self-respect and feeling of pride in our school. Many students see this damage and lose some pride in their school.What , then can we do to prevent vandalism in school? First of all, we need to make students come to realize the importance of taking care of public property. School property should be treated with care so that it can be used by all the students. Therefore, damaging school property means damaging the enjoyment or other students. If we can explain this to students, then they will be less likely to damage school property when they know that it will not only pollute the environment but also hurt themselves as well.Secondly, we should learn to observe school rules and regulations. These rules and regulations are there to look after both the students and the school. Whenever we see any acts of vandalism, we need to remind the people of the rules and try to prevent these acts from happening. If it is serious vandalism, we need to report it to the teacher or parents.Thirdly, anyone who vandalizes school property should receive some kind of punishment. For example, if someone has torn a page from a library book, he or she would have to carefully tape the page back into the book, making an apology for a librarian. If someone write or draws on a desk, he or she should stay behind after school and clean all the desks in the classroom. Such punishment is not harsh, but can make them conscious of their misbehavior.Vandalism costs schools money that could be better spent on educating students, and it harms students’ pride in their school as well. If we educate students about vandalism and work to prevent it from happening, then we will begin to see cleaner schools、bright classrooms and happier students.In a word, as students, we should keep some do’s and don’ts in our mind to guide our behavior in school. At the same time, we are trying hard to get id of our bad habits, to be a civilized student.二As the Arctic warms, greenhouse gases will be released from thawing（融化）permafrost（永久冻土）faster and at significantly higher levels than previous estimates, according to survey results from 41 international scientists published in the Nov. 30 issue of the journal Nature. Permafrost thaw will release approximately the same amount of carbon as deforestation森林开伐, say the authors, but the effect on climate will be 2.5 times bigger because emissions发射include methane（甲烷）, which has a greater effect on warming than carbon dioxide.The survey, led by University of Florida researcher Edward Schuur and University of Alaska Fairbanks graduate student Benjamin Abbott, asked climate experts what percentage of the surface permafrost is likely to thaw, how much carbon will be released and how much of that carbon will be methane. The authors estimate that the amount of carbon released by 2100 will be 1.7 to 5.2 times larger than reported in recent modeling studies, which used a similar warming scenario（局面）."The larger estimate is due to the inclusion（包含）of processes missing from current models and new estimates of the amount of organic carbon stored deep in frozen soils," Abbott said. "There's more organic carbon in northern soils than there is in all living things combined; astonishingly Northern soils hold around 1,700 billion tons of organic carbon, around four times more than all the carbon ever emitted by modern human activity and twice as much as is now in the atmosphere, according to the latest estimate. When permafrost thaws, organic material in the soil decomposes(分解) and releases gases such as methane and carbon dioxide."In most ecosystems organic matter is concentrated only in the top meter of soils, but when arctic soils freeze and thaw the carbon can work its way many meters down, said Abbott, who studies how carbon is released from collapsed收缩的landscapes -- a process not accounted for in current models. Until recently that deep carbon was not included in soil inventories and it still is not accounted for in most climate models."We know about a lot of processes that will affect the fate of arctic carbon, but we don't yet know how to mix them into climate models," Abbott said. "We're hoping to identify some of those processes and help the models catch up."Most large-scale models assume that permafrost warming depends on how much the air above the permafrost is warming. Missing from the models, say the authors, are processes such as the effects of abrupt thawing that can melt an ice wedge(冰楔), result in collapsed ground and accelerate additional thawing."This survey is part of the scientific process, what we think is going to happen in the future, and how we come up with testable hypotheses for future research," Schurr said. "Our survey outlines the additional risk to society caused by thawing of the frozen North and the need to reduce fossil fuel use and deforestation."By combining data from previous models with expert predictions the authors hope to provide a frame of reference(参照标准) for scientists studying all aspects of climate change. "Permafrost carbon release is not going to overshadow fossil fuel emissions as the main driver of climate change" said Schuur, "but it is an important amplifier（放大器）of climate change."三Researchers at Sweden's KTH Royal Institute of Technology say they have found further proof that the wolf ancestors of today's domesticated (驯化)dogs can be traced to southern East Asia -- findings that run counter to(违反)theories placing the cradle（摇篮，发源地）of the canine （似犬的）line in the Middle East. Dr Peter Savolainen, KTH researcher in evolutionary genetics(遗传学), says a new study released Nov. 23 confirms that an Asian region south of the Yangtze River was the principal and probably only region in which wolves were domesticated(家养的) by humans.Data on genetics, morphology（形态学）and behaviour show clearly that dogs are from wolves, but there's never been scientific consensus（一致，舆论）on where in the world the domestication process began. "Our analysis of Y-chromosomal(染色体的) DNA now confirms that wolves were first domesticated in Asia south of Yangtze River -- we call it the ASY region -- in southern China or Southeast Asia," Savolainen says.The Y data supports previous evidence from DNA. "Taken together, the two studies provide very strong evidence that dogs originated in the ASY region," Savolainen says.Archaeological(考古学的) data and a genetic study have recently been published in Nature suggest that dogs originate from the Middle East. But Savolainen rejects that view. "Because none of these studies included samples from the ASY region, evidence from ASY has been overlooked," he says.Peter Savolainen and PhD student Mattias Oskarsson worked with Chinese colleagues to analyze DNA from male dogs around the world. Their study was published in the scientific journal Heredity（遗传）.Approximately half of the gene pool was universally shared everywhere in the world, while only the ASY region had the entire range of genetic diversity. "This shows that gene pools in all other regions of the world most probably originate from the ASY region," Savolainen says."Our results confirm that Asia south of the Yangtze River was the most important -- and probablythe only -- region for wolf domestication, and that a large number of wolves were domesticated," says Savolainen.In separate research published recently in Ecology and Evolution, Savolainen, PhD student Arman Ardalan and Iranian and Turkish scientists studied mitochondrial（线粒体）DNA carefully , with a particular focus on the Middle East. Because mitochondrial DNA is inherited(遗传而得) only from the mother in most species, it is especially useful in studying evolutionary relationships进化关系."Since the studies have indicated that dogs from wolves can be traced to the Middle East, we wanted to be sure nothing had been missed. We find no signs whatever that dogs originated there," says Savolainen.In their studies, the researchers also found minor(较小的)genetic contributions from crossbreeding(杂交繁育) between dogs and wolves in other geographic regions, including the Middle East."This subsequent (随后的)dog/wolf hybridization（杂交）contributed only modestly谨慎地；四Global food demand could double by 2050, according to a new projection by David Tilman, Regents Professor of Ecology in the University of Minnesota's College of Biological Sciences, and colleagues, including Jason Hill, assistant professor in the College of Food, Agricultural and Natural Resource Sciences. Producing that amount of food could significantly increase levels of carbon dioxide and nitrogen（氮）in the environment and cause the extinction of numerous species. But this can be avoided, the paper shows, if the high-yielding technologies of rich nations are adapted to work in poor nations, and if all nations use nitrogen fertilizers more efficiently. "Agriculture's greenhouse gas emissions could double by 2050 if current trends in global foodproduction continue," Tilman said. "Global agriculture already accounts for a third of all greenhouse gas emissions." Much of these emissions come from land clearing, which also threatens species with extinction.The article shows that if poor nations continue current practices, they will clear a land area larger than the United States (two and a half billion acres) by 2050. But if richer nations help poorer nations improve yields to achievable levels, that could be reduced to half a billion acres.The research, published Nov. 21 online by the Proceedings of the National Academy of Sciences, shows that adopting nitrogen-efficient "intensive(集中)" farming can meet future global food demand with much lower environmental impacts than the "extensive" farming practiced by many poor nations, which clear land to produce more food. The potential benefits are great. In 2005, crop yields(粮食产量) for the wealthiest nations were more than 300 percent higher than yields for the poorest nations."Strategically intensifying(战略性强化) crop production in developing and least-developed nations would reduce the overall environmental harm caused by food production, as well as provide a more equitable(平衡法的)food supply across the globe," said Hill.The Food and Agriculture Organization (FAO) of the United Nations recently projected (规划)a 70 percent increase in demand. According to Tilman, either projection shows that the world faces major environmental problems unless agricultural practices change.The environmental impacts of meeting demand depend on how global agriculture expands. Clearing land for agriculture and the use of fuel and fertilizers to grow crops increases carbon and nitrogen in the environment and causes species extinctions.In the paper, Tilman and his collaborators explore different ways of meeting demand for food and their environmental effects. In essence(实质上), the options are to increase productivity on existing agricultural land, clear more land, or do a combination of both. They consider various plans in which the amount of nitrogen use, land cleared, and resulting greenhouse gas emissions differ."Our analyses show that we can save most of the Earth's remaining ecosystems生态系统by helping the poorer nations of the world feed themselves," Tilman said.Christian Blazer, from the University of California Santa Barbara, collaborated with Tilman and Hill on the research. Belinda Befort, University of Minnesota College of Biological Sciences, also五Ever wondered why flies are attracted to beer? Entomologists（昆虫学家）at the University of California, Riverside have, and offer an explanation. They report that flies sense glycerol（甘油）, a sweet-tasting compound that yeasts(酵母) make during fermentation（发酵）. "Insects use their taste system to glean（收集）important information about the quality and nutritive value营养值of food sources," said Anupama Dahanukar, an assistant professor of entomology, whose lab conducted the research. "Sugars signal high nutritive value to flies, but little is known about which chemical cues(线索；提示)flies use for food sources that are low in sugar content -- such as beer." Dahanukar's lab examined the feeding preference（偏爱，倾向）of the common fruit fly for beer and other products of yeast fermentation, and found that a receptor(受体) (a protein that serves as a gatekeeper) that is associated with neurons(神经细胞) located in the fly's mouth-parts is instrumental(有助于) in signaling a good taste for beer.The receptor in question is Gr64e. Once a fly has settled on beer, Gr64e detects glycerol and transmits this information to the fly's neurons, which then influences the fly's behavioral response. Dahanukar explained that flies use other receptors in their sensory organs to find food from a distance."Taste becomes important only after the fly makes physical contact with food," she said. "A fly first locates food sources using its odor receptors -- crucial for its long-range attraction to food. Then, after landing on food, the fly uses its taste system to sample the food for suitability in terms of nutrition and toxicity毒性."Dahanukar, a member of UCR's Institute for Integrative Genome Biology, explained that taste receptors also come into play when a female fly has to locate a suitable site for laying eggs. "Females come to a decision after they have conducted intense probing(认真地探索) of various potential sites," she said.Study results appeared online Nov. 6 in Nature Neuroscience.Dahanukar was joined in the project by Zev Wisotsky, Adriana Medina, and Erica Freeman -- all of whom work in her lab.Wisotsky, a neuro神经science graduate student and the first author of the research paper, performed the imaging, taste electrophysiology and behavior experiments. He was joined in his efforts by Freeman, a bioengineering graduate student, who performed the olfactory（嗅觉的）recordings; and Medina, a junior specialist in entomology昆虫学, who performed the feeding preference experiments and molecular analysis分子分析.The lab is poised now to move the research forward."How do you get information from the chemical environment to the brain -- not just in flies but other insects as well?" Dahanukar said. "How is that information processed to give rise to appropriate behavior? How does feeding behavior change with hunger? These are some questions we would like pursue(寻求)."The research project was supported in part by a Whitehall Foundation research grant(授予) to Dahanukar and a fellowship(奖学金）from the National Science Foundation Integrated Graduate六If your family is like many in the United States, unloading the week’s grocerie s includes hauling a case or two of bottled water into your home. On your way to a soccer game or activity, it’s easy to grab a cold one right out of the fridge, right?But all those plastic bottles use a lot of fossil fuels and pollute the environment. In fact, Americans buy more bottled water than any other nation in the world, adding 29 billion water bottles a year to the problem. In order to make all these bottles, manufacturers use 17 million barrels of crude oil. That’s enough oil to keep a million ca rs going for twelve months.Imagine a water bottle filled a quarter of the way up with oil. That’s about how much oil was needed to produce the bottle.So why don’t more people drink water straight from the kitchen faucet? Some people drink bottled water b ecause they think it is better for them than water out of the tap, but that’s not true. In the United States, local governments make sure water from the faucet is safe. There is also growing concern that chemicals in the bottles themselves may leach into the water.People love the convenience of bottled water. But maybe if they realized the problems it causes, they would try drinking from a glass at home or carrying water in a refillable steel container instead of plastic.Plastic bottle recycling can help—instead of going out with the trash, plastic bottles can be turned into items like carpeting or cozy fleece clothing.Unfortunately, for every six water bottles we use, only one makes it to the recycling bin. The rest are sent to landfills. Or, even worse, they end up as trash on the land and in rivers, lakes, and the ocean. Plastic bottles take many hundreds of years to disintegrate.Water is good for you, so keep drinking it. But think about how often you use water bottles, and see if you can make a change.Betty McLaughlin, who runs an organization called the Container Recycling Institute, says we should try using fewer bottles: “If you take one to school in your lunch, don’t throw itaway—bring it home and refill it from the tap for the next day. Keep track of how many times you refill a bottle before you recycle it.”And yes, you can make a difference. Remember this: Recycling one plastic bottle can save enough一、1.solving. 2. without. 3. caring. 4. carefully. 5. available. 6. damage/destruct. 7. purpose 8. vandalizing9. punished. 10. seeing.二、1.rate/speed 2. carbon 3. including 4. influencing 5. amounts 6. In 7. which 8. over 9. breaks10. aim/purpose/goal三、1. South 2.where 3. shown 4. no 5. convince 6. which 7. published 8. study 9. particularly 10. so四、1.faced 2.changed 3. add 4. destroyed 5. causing 6. appear 7. threatening 8. adapt 9. left 10. less五、1.tasting 2. gathered 3. using 4. send 5. that 6. link 7. become 8. samples 9. work 10. reach六、1.Present 2. most 3. Reasons 4. quality 5. convenient 6. production / manufacturing7. pollution 8. Suggestions / Tips 9. made 10. possible。