单选题Rubidium, potassium and carbon are three common elements used to date the history of Earth. The rates of radioactive decay of these elements are absolutely regular when averaged out over a period of time; nothing is known to change them. To be useful as clocks, the elements have to be fairly common in natural minerals, unstable but decay slowly over millions of years to form recognizable "daughter" products which are preserved minerals. For example, an atom of radioactive rubidium decays to form an atom of strontium (another element) by converting a neutron in its nucleus to a proton and releasing an electron, generating energy in the process. The radiogenic daughter products of the decay-in this case strontium atoms--diffuse away and are lost above a certain very high temperature. So by measuring the exact proportions of rubidium and strontium atoms that are present in a mineral, researchers can work out how long it has been since the mineral cooled below that critical "blocking" temperature. The main problems with this dating method are the difficulty in finding minerals containing rubidium, the accuracy with which the proportions of rubidium and strontium are measured, and the fact that the method gives only the date when the mineral last cooled below the blocking temperature. Because the blocking temperature is very high, the method is used, mainly for recrystallized (igneous or metamorphic) rocks, not for sediments--rubidium-bearing minerals in sediments simply record the age of cooling of the rocks which were eroded to form the sediments, not the age of deposition of the sediments themselves. Potassium decays to form (a gas) which is sometimes lost from its host mineral by escaping through pores. Although potassium-argon dating is therefore rather unreliable, it can sometimes be useful in dating sedimentary rocks because potassium is common in some minerals which form in sediments at low temperatures. Assuming no argon has escaped, the potassium-argon date records the age of the sediments themselves. Carbon dating is mainly used in archaeology. Most carbon atoms (carbon-12) are stable and do not change over time. However, cosmic radiation bombarding the upper atmospheres constantly interacting with nitrogen in the atmosphere to create an unstable form of carbon, carbon-14.

单选题Suzan Fellman had a hard time with Laura Bush's redo of the famed guest quarters named for President Lincoln: "Looking at it, I thought I was in a Radisson lobby somewhere in the Midwest long ago. I could not imagine spending a night in that space." Done up with Victorian furnishings, the Lincoln Bedroom is one of the residence's least-changed spaces, said Betty Monkman, formerly chief curator of the White House for nearly 40 years. "It's a quasi-museum room," she said, "with a lot of objects, such as the bed, that have symbolic importance." The elaborately carved bed bought for Lincoln is the centerpiece of the room. According to historian William Scale, the president was furious that his wife, Mary, spent so much money redecorating the White House during a time of war. He never slept in the bed, and the ornate piece eventually was moved to a spare room. Los Angeles designer Fellman saw parallels, calling the Obama era a period of "pulling back on extravagance." It is a good time, she said, to revisit pieces in storage, to rearrange old furniture in a new fashion, and use paint and fabrics to bring life and fun into a room without spending a fortune. In this re-imagining of the Lincoln Bedroom, Fellman would retain the legendary bed but paint the ceiling a sky blue and use a Cecil Beaton rose-print fabric for curtains. "Lincoln loved roses," Fellman said, "and this beige and ivory version keeps it from being too bold, modern or feminine." At a time when Americana is expected to stage a strong revival, Fellman said traditional styles such as Colonial and Federal can co-exist with European antiques if they are balanced in scale. Mindful of the recession, the designer advocated selecting furniture with longevity in mind. "If you are going to spend money, buy quality things that you never want to get rid of," she said. "A couple of really good things can make all the difference in a room." Her splurges would include a camel-hair sofa, which Fellman said was long-lasting and timeless. As a Pop Art-influenced statement about thrift, a custom rug woven with a 6-foot-diameter medallion replicates the penny's image of Lincoln in subtle shades of ivory and copper. In bad times as in good, spare rooms don't have to be grand to be effective, Fellman said. "A guest room should feet inviting and intimate," she said "It has to exude serenity./

单选题Passage 4 As the pace of life continues to increase, we are fast losing the art of relaxation. Once you are in the habit of rushing through life and working from morning till night, it is hard to slow down. But relaxation is essential for a healthy mind and body. Stress is a natural part of everyday life and there is no way to avoid it. In fact, it is not the bad thing it is often supposed to be. A certain amount of stress is vital to provide motivation and give purpose to life. It is only when the stress gets out of control that it can lead to poor performance and ill health. The amount of stress a person can withstand depends very much on the individual. Some people are not afraid of stress and such characters are obviously prime material for managerial responsibilities. Others lose heart at the first signs of unusual difficulties. When exposed to stress, in whatever form, we react both chemically and physically. In fact we make choice between "flight or fight" and in more primitive days the choices made the difference between life or death. The crises we meet today are unlikely to be so extreme, but however little the stress, it involves the same response. It is when such a reaction lasts long, through continued exposure to stress, that health becomes endangered. Such serious conditions as high blood pressure and heart diseases have established links with stress. Since we cannot remove stress from our lives it would be unwise to do so even if we could, we need to find ways to deal with it.

单选题The worsening financial situation made it obvious that an economic depression was ______.

单选题{{B}}Passage One{{/B}} Some psychologists maintain that mental acts such as thinking are not performed in the brain alone, but that one's muscles also participate. It may be said that we think with our muscles in somewhat the same way that we listen to music with our bodies. You surely are not surprised to be told that you usually listen to music not only with your ears but with your whole body. Few people can listen to music that is more or less familiar without moving their body or, more specifically, some part of their body. Often when one listens to a symphonic concert on the radio, he is tempted to direct the orchestra even though he knows there is a competent conductor on the job. Strange as this behavior may be, there is a very good reason for it. One cannot derive all possible enjoyment from music unless he participates, so to speak, in its performance. Tile listener "feels" himself into the music with more or less pronounced motions of his body. The muscles of the body actually participate in the mental process of thinking in the same way, but this participation is less obvious because it is less pronounced.

单选题Why are you always suspicious ______ anyone who is kind to you?

单选题 Sunny periods will be interspersed with occasional showers.

单选题As I recall my plane trip around the world last July and August, I think my difficulty was the adjustment to the different ______ served with the food in the various cities we visited.

单选题{{B}}Passage Four{{/B}} More than 11,000 traffic lights and "Don't Walk" signals in New York City have been switched to light-emitting diodes that use 90 percent less energy than conventional fixtures. More than 180,000 energy-guzzling refrigerators in public housing projects have been replaced with new ones that use a quarter of the power of the old ones. For years, New York has been the city that not only never sleeps, but the city that hardly ever remembers to turn the lights out. On the coldest days of winter, New Yorkers raise their windows to let out the heat. In the dog days of summer, a husky could freeze in the open doorway of a Fifth Avenue boutique. But now, measures like more efficient traffic lights and refrigerators are speeding up a long trend making New York one of the most energy-efficient cities in the nation--and officials in cities like Portland and Seattle that might, in the public mind, seem more environmentally conscious are taking notice. Though the savings represent just a portion of the 5 billion kilowatt-hours of electricity the entire city uses in a year, the innovation and ease of the efficiency measures have attracted attention. New York's energy diet is based on a simple formula--a blend of local legislation, state assistance and an awareness of the city's own position as an 800-pound gorilla in the energy market. "Eventually what happens here starts to hap-pen around the country," said Ashok Gupta, director of the air and energy program for the Natural Resources Defense Council. "The market that New Yorkers provide is clearly an important factor in moving the rest of the country. That's the way markets work." And that market dynamic helps make New York an energy efficiency laboratory. Environmental groups expend much of their own energy to help shape legislation in New York because they realize that it is an efficient way to kick-start national programs. Manufacturers are also attuned to New York's latest trends and needs because the market is simply too big to ignore. "What's different here is that we are promoting the idea of energy efficiency, using less energy and not necessarily saying that anyone has to do without," said Eugene W. Zehman, president of the New York Power Authority. "If we use energy more wisely there will be more energy for people to consume and less energy for us to produce." "Counter to what most non-New Yorkers might think, New York is a very progressive city for green building," said Jim Himes, director of the Enterprise Foundation office in New York. The mass transit system, multifamily housing, mixed neighborhoods and the fact that developments never go up on virgin land anymore, all make building in New York very energy-efficient. "It's easier to be green here." Mr. Himes said.

单选题"I am sure you shan"t find a single mistake in my composition." "Oh, I shan"t, ______?"

单选题The government allocated a special sum of money in order to reinforce the prosecution of the effective policy.

单选题Americans often say that there are only two things a person can be sure of in life: death and taxes. Americans do not have a comer on the "death" market, but many people feel that the United States leads the world with the most taxes. Taxes consist of the money which people pay to support their government. There are generally three levels of government in the United States: federal, state, and city: therefore, there are three types of taxes. Salaried people who earn more than a few thousand dollars must pay a certain percentage of their salaries to the federal government. The percentage varies from person to person. It depends on their salaries. The federal government has a graduated income tax, that is, the percentage of the tax increases as a person"s income increase. With the high cost of taxes, people are not very happy on April 15, when the federal taxes are due. The second tax is for the state government: New York, California, or any of the other forty-eight states. Some states have an income tax similar to that of the federal government. Of course, the percentage for the state tax is lower. Other states have a sales tax, which is a percentage charged to any item which you buy in that state. For example, a person might want to buy a packet of cigarettes for twenty-five cents. If there is a sales tax of eight percent in that state, then the cost of the cigarettes is twenty-seven cents. This figure includes the sales tax. Some states use income tax in addition to sales tax to raise their revenues. The state tax laws are diverse and confusing. The third tax is for the city. This tax comes in two forms: property tax (people who own a home have to pay taxes on it) and excise tax, which is charged on cars in a city. The cities use these funds for education, police and fire department, public works and municipal buildings. Since Americans pay such high taxes, they often feel that they are working one day each week just to pay their taxes. People always complain about taxes. They often protest that the government uses their tax dollars in the wrong way. They say that it spends too much on useless and impractical programs. Although Americans have different view on many issues, they tend to agree on one subject: taxes are too high.

单选题If you don't ______ smoking, you'll never get better. A. give off B. give out C. giver over D. give up

单选题 The most damning thing that can be said about the world's hest-endowed and richest country is that it is not only not the leader in health status, but that it is so low in the ranks of the nations. The United States ranks 18th among nations of the world in male life expectancy at birth, 9th in female life expectancy at birth, and 12th in infant mortality. More importantly, huge variations are evident in health status in the United States from one place to the next and from one group to the next. The forces that affect health can be aggregated into four groupings that lends to analysis of all health problems. Clearly the largest aggregate of forces resides in the person's environment. His own behavior, in part derived from his experiences with his environment, is the next greatest force affecting his health. Medical care services, treated as separate from other environmental factors because of the special interest we have in them, make a modest contribution to health status. Finally the contributions of heredity to health are difficult to judge. We are templated at conception as to our basic weaknesses and strengths, but many hereditary attributes never become manifest because of environmental and behavioral forces which act before the genetic forces come to maturity, and other hereditary attributes are increasingly being palliated by medical care. No other country spends what we do per capita for medical care. The care available is among the best technically, even if used too lavishly and thus dangerously, but none of the countries which stand above us in health status have such a high proportion of medically disenfranchised persons. Given the evidence that medical care is not that valuable and access to care not that bad, it seems most unlikely that our bad showing is caused by the significant proportion who are poorly served. Other hypotheses have greater explanatory power: excessive poverty, both actual and relative, and excessive affluence. Excessive poverty is probably more prevalent in the U.S. than in any of the countries that have a better infant mortality rate and female life expectancy at birth. This is probably true also for all but four or five of the countries with a longer male life expectancy. In the notably poor countries that exceed us in male survival, difficult living conditions are a more accepted way of life and in several of them, a good basic diet, basic medical care and basic education, and lifelong employment opportunities are an everyday fact of life. In the U. S. a national unemployment level of 10 percent may be 40 percent in the ghetto(黑人居住地) while less than 4 percent elsewhere. The countries that have surpassed us in health do not have such severe or entrenched problems. Nor are such a high proportion of their people involved in them. Excessive affluence is not so obvious a cause of ill health, but, at least until recently, few other nations could afford such unhealthful ways of living. Excessive intake of animal protein and fats, dangerous imbibing of alcohol and use of tobacco and drugs (prescribed and proscribed), and dangerous recreational sports and driving habits are all possible only because of affluence. Our heritage, desires, opportunities, and our machismo, combined with the relatively low cost of bad foods and speedy vehicles, make us particularly vulnerable to our affluence. And those who are not affluent try harder. Our unacceptable health status, then, will not be improved appreciably by expanded medical resources nor by their redistribution so much as by a general attempt to improve the quality of life for all.

单选题Their diplomatic principles completely laid bare their ______ for world conquest.

单选题Faced with rapid inflation and shrinking international and home markets, many companies have declared______.