单选题On this trip, Frank made a Ucoordinated/U effort to get along with the press.

单选题The shrapnel {{U}}maimed{{/U}} the young soldier.

单选题The city has decided to {{U}}do away with{{/U}} all the old buildings in its center. A.get rid of B.set up C.repair D.paint

单选题下面有3篇短文，每篇短文后有5道题，每题后面有4个选项。请仔细阅读短文并根据短文回答其后面的问题，从4个选项中选择1个最佳答案。{{B}}第一篇{{/B}} {{B}}Sugar Power for Cell Phones{{/B}} Using enzymes commonly found in living cells, a new type of fuel cell produces small amounts of electricity from sugar. If the technology is able to succeed in mass production, you may some day share your sweet drinks with your cell phone. In fuel cells, chemical reactions generate electrical currents. The process usually relies on precious metals, such as platinum. In living cells, enzymes perform a similar job, breaking down sugars to obtain electrons and produce energy. When researchers previously used enzymes in fuel cells, they had trouble keeping them active, says Shelley D. Minteer of St Louis University. Whereas biological cells continually produce fresh enzymes, there's no mechanism in fuel ceils to replace enzymes as they quickly degrade. Minteer and Tamara Klotzbach, also of St Louis University, have now developed polymers that wrap around an enzyme and preserve it in a microscopic pocket. "We tailor these pockets to provide the ideal microenvironment" for the enzyme, Minteer says. The polymers keep the enzyme active for months instead of days. In the new fuel cell, tiny polymer bags of enzyme are embedded in a membrane that coats one of the electrodes. When glucose from a sugary liquid gets into a pocket, the enzyme oxidizes it, releasing electrons and protons. The electrons cross the membrane and enter u wire through Which they travel to the other electrode, where they react with oxygen in the atmosphere to produce water. The flow of electrons through the wire constitutes an electrical current that can generate power. So far, the new fuel cells don't produce much power, but the fact that they work at all is exciting, says Paul Kenis, a chemical engineer at the University of Illinois at Urbana-Champaign. "Just getting it to work," Kenis says, "is a major accomplishment." Sugar-eating fuel cells could be an efficient way to make electricity. Sugar is easy to find. And the new fuel cells that mn on it are biodegradable,, so the technology wouldn't hart the environment. The scientists are now trying to use different enzymes that will get more power from sugar. They predict that popular products may be using the new technology in as little as 3 years.

单选题Rock climbing is hazardous .

单选题Ants as a Barometer of Ecological Change At picnics, ants are pests. But they have their uses. In industries such as mining, farming and forestry ,they can help gauge (测量) the health of the environment by just crawling around and being antsy. It has been recognized for decades that ants—which are highly sensitive to ecological change—can provide a near-perfect barometer of the state of all ecosystem. Only certain species, for instance, will continue to thrive (兴旺, 欣欣向荣)at a forest site that has been cleared of trees. Others will die out for lack of food. And still others will move in and take up residence. By looking at which species populate a deforested area, scientists can determine how "stressed" the land is. They do this by sorting the ants, counting their numbers and comparing the results with those of earlier surveys. Ants are used simply because they are so common and comprise so many species. Where mine sites are being restored, for example, some ant species will recolonize the stripped land more quickly than others. This allowed scientists to gauge the pace and progress of the ecological recovery. Australian mining company Capricorn Coal Management has been successfully using ant surveys for years to determine the rate of recovery of land that it is replanting near its German Creek mine in Queensland. Ant surveys also have been used with mine—site recovery projects in Africa and Brazil, where Warm climates encourage dense and diverse ant populations. "We found it worked extremely well there, "says Jonathan Majer, a professor of environmental biology. Yet the surveys are perfectly suited to climates throughout Asia, he says, because ants are so common throughout the region. As Majer puts it. "That's the great thing about ants. " Ant surveys are so highly-regarded as ecological indicators that governments worldwide accept their results when assessing the environmental impact of mining and tree harvesting. Yet in other businesses, such as farming and property development, ant surveys aren't used widely. Why not? Because many companies can't afford the expense or the laboratory time needed to sift(细查, 祥查) results for a comprehensive survey. The cost stems, also, from the scarcity of ant species.

单选题It is often claimed that nuclear energy is something we cannot do without. We live in a consumer society where there is an enormous demand for commercial products of all kinds. Moreover, an increase in industrial production is considered to be one solution to the problem of mass unemployment. Such an increase presumes an abundant and cheap energy supply. Many people believe that nuclear energy provides an inexhaustible and economical source of power and that it is therefore essential for an industrially developing society. There are a number of other advantages in the use of nuclear energy. Firstly, nuclear power, except for accidents, is clean. A further advantage is that a nuclear power station can be run and maintained by relatively few technical and administrative staff. The nuclear reactor represents an enormous step in our scientific evolution and, whatever the anti-nuclear group says, it is wrong to expect a return to more primitive sources of fuel. However, opponents of nuclear energy point out that nuclear power stations bring a direct threat not only to the environment but also to civil liberties. Furthermore, it is questionable whether ultimately nuclear power is a cheap source of energy. There have, for example, been very costly accidents in America, in Britain and, of course, in Russia. The possibility of increases in the cost of uranium (铀) in addition to the cost of greater safety provisions could price nuclear power out of the market. In the long run, environmentalists argue, nuclear energy wastes valuable resources and disturbs the ecology to an extent which could bring about the destruction of the human race. Thus, if we wish to .survive, we cannot afford nuclear energy. In spite of the case against nuclear energy outlined above, nuclear energy programmes are expanding. Such an expansion assumes a continual growth in industrial production and consumer demands. However, it is doubtful whether this growth, will or can continue. Having weighed up the arguments on both sides, it seems there are good economic and ecological reasons for sources of energy other than nuclear power.

单选题Think as a Hacker Does At the brand-new Hacker Academy in Chicago, US, students learn about phishing schemes, firewall breaches, and advanced tricks for breaking into confidential documents and revealing passwords. But it's not nearly as illegal as it sounds. The academy doesn't teach people to be (51) , but to "think like hackers" and hopefully to stay one step ahead of (52) . The students are (53) computer security professionals. They attend a course that teaches them the tools and techniques that hackers could use to get (54) systems they're trying to protect. They (55) a certificate in "ethical hacking" if they graduate. The academy is one of the growing number of organizations that teach IT security experts to think like their enemies and to find holes in their systems (56) the hackers do. "If you can think like a hacker, you're able to (57) some of the attacks that are happening," said Aaron Cohen, the academy's founder. Those attacks can range from indiscriminate viruses to corporate spying and efforts to gain sensitive data (58) banks, credit card companies, or individuals. Computer Economics, a US IT research firm, estimates the (59) caused by viruses and other attacks in 2006 to be somewhere around US$14 billion. "While the massive viruses seem to be (60) in number, there are more targeted attacks," said Mark McManus of Computer Economics. With ransom attacks, for instance, hackers will break into a company's network, and threaten to destroy it or give information to a competitor (61) they're not paid. Given all the threats, many companies are sending IT professionals to courses like those Cohen offers. So the "ethical hacker" certification, offered by the New York-based International Council of Electronic Commerce Consultants (the EC-Council), (62) about. The EC-Council says it has trained about 20,000 people in 60 countries over the past three years, with 8,000 of them passing a (63) and earning the "ethical hacker" certification. Cohen's list of interested people includes an FBI agent, NASA employees, independent consultants, and company IT security directors. Some want the five-day on-site certification course. Others want a quick overview, like the US$ 695 "midnight hacking" course, given online and late at (64) . Cohen doesn't (65) much about students using their courses for evil purposes. "Hackers don't need our help," says Cohen.

单选题The Uodds/U against you winning the national lottery are millions to one.

单选题Renewable Energy Sources Today petroleum (石油) provides around 40% of the world's energy needs, mostly fuelling automobiles. Coal is still used, mostly in power stations, to cover one-quarter of our energy needs, but it is the least efficient, unhealthiest and most environmentally damaging fossil fuel (矿物燃料). Natural gas reserves could fill some of the gap from oil, but reserves of that will not last into the 22nd century either. Most experts predict we will exhaust easily accessible reserves within 50 years. Less-polluting renewable energy sources offer a more practical long-term energy solution. "Renewable" refers to the fact that these resources are not used faster than they can be replaced. Hydroelectric (水力发电的) power is now the most common form of renewable energy, supplying around 20% of world electricity. China's Three Gorges Dam is the largest ever. At five times the size of the US's Hoover Dam, its 26 turbines (涡轮机) will generate the equivalent energy of 18 coal-fired power stations. It will satisfy 3% of China's entire electricity demand. In 2003, the first commercial power station to use tidal (潮汐的) currents in the open sea opened in Norway. It is designed like windmill (风车), but others take the form of turbines. As prices fall, wind power has become the fastest growing type of electricity generation—quadrupling (翻两番) worldwide between 1999 and 2005. Modern wind farms consist of turbines that generate electricity. Though it will be more expensive, there is more than enough wind to provide the world's entire energy needs. Wind farms come in onshore and offshore forms. They can often end up at spots of natural beauty, and are often unpopular with residents. And turbines are not totally harmless—they can interfere with radar, alter climate and kill sea birds. Scotland is building Europe's largest wind farm, which will power 200,000 homes. The UK's goal is to generate one-fifth of power from renewable sources, mainly wind, by 2020. But this may cause problems, because wind is unreliable.

单选题下面的短文有15处空白，请根据短文内容为每处空白确定1个最佳选项。 Cell Phone Lets Your Secret Out Your cell phone holds secrets about you. Besides the names and {{U}}(51) {{/U}} that you've programmed into it, traces of your DNA linger on the device, according to a new study. DNA is genetic material that {{U}}(52) {{/U}} in every cell. Like your fingerprint, your DNA is unique to you {{U}}(53) {{/U}} you have an identical twin. Scientists today routinely analyze DNA in blood, saliva, or hair left {{U}}(54) {{/U}} at the scene of a crime. The results often help detectives identify {{U}}(55) {{/U}} and their victims. Your cell phone can reveal more about you {{U}}(56) {{/U}} you might think. Method J. McFadden, a scientist at McMaster University in Hamilton, Ontario, heard about a crime in which the suspect bled onto a cell phone and later dropped the {{U}}(57) {{/U}}. This made her wonder whether traces of DNA lingered on cell phones—even when no blood was involved. {{U}}(58) {{/U}}she and colleague Margaret Wallace of the City University of New York analyzed the flip-open phones of 10 volunteers. They used swabs to collect {{U}}(59) {{/U}} traces of the users from two parts of the phone: the outside, where the user holds it, and the {{U}}(60) {{/U}} , which is placed at the user's ear. The scientists scrubbed the phones using a solution made mostly {{U}}(61) {{/U}} alcohol. The aim of washing was to remove all detectable traces of DNA. The owners got their phones {{U}}(62) {{/U}} for another week. Then the researchers collected the phones and repeated the swabbing of each phone once more. The scientists discovered DNA that {{U}}(63) {{/U}} to the phone's speaker on each of the phones. Better samples were collected from the outside of each phone, but those swabs also picked up DNA that belonged to other people who had apparently also handled the phone. {{U}}(64) {{/U}}, DNA showed up even in swabs that were taken immediately after the phones were scrubbed. That suggests that washing won't remove all traces of evidence from a criminal's device. So cell phones can now be added to the {{U}}(65) {{/U}} of clues that can clinch a crime-scene investigation.

单选题What is the author’s tone toward the Northern Lights?

单选题Under the {{U}}terms{{/U}} of the contract, you must give 3 months’ notice before you leave.

单选题Michael is now merely a good friend. A．largely B．barely C．just D．rarely

单选题The city has decided to do away with all the old buildings in its center.

单选题There is no risk to public health. A. point B. danger C. chance D. hope

单选题It was Uan exceptionally/U hot day for the time of year.

单选题I can't put up with my neighbor's noise any longer, it's driving me mad.A. tolerateB. generateC. reduceD. measure

单选题The landscape can change Uabruptly/U after a rainstorm in the Great Sahara Desert.

单选题Plants in Desert Only special plants can survive the terrible climate of a desert, for these are regions when the annual range of the soil temperature can be over 75℃. Furthermore, during the summer there are few clouds in the sky to protect plans from the sun' s ray. Another problem is the fact that there are frequently strong winds that drive small, sharp particles of sand into the plants,earing and damaging them. The most difficult probiem for all forms of plant life, however, is the fact that the entire annual rainfall occurs during a few days or weeks in spring. Grasses and flowers in desert survive from one year to the next by existing through the long, hot, dry season in the form of seeds. These seeds remain inactive unless the fight amount of'rain falls. If no rain falls, or if insufficient rain falls, they wait until the next year, or even still the next. Another factor that helps these plants to survive is the fact that their life cycles are short. By the time the water from the spring rains disappears — just a few weeks after it falls — such plants no longer need any. The perennials (多年生植物) have special features that enable them to survive as plants for several years. Thus, nearly all desert perennials have extensive root systems below ground and a small shoot system above ground. The large root network enables the plant to absorb as much water as possible in short time. The small shoot system, on the other hand, considerably limits water loss by evaporation. Another feature of many perennials is that after the rainy season they 10se their leaves in preparation for the long, dry season, just as trees in wetter climates lose theirs in preparation for the winter. This reduces their water loss by evaporation (蒸发) duing the dry season. Then, in next rainy season, they come fully alive once more, and grow new branches, leaves and flowers, just as the grasses and flowers in desert do.