单选题We cannot compel you to do it, but we think you should.

单选题The audience applauded enthusiastically after the performance at the Grand Old Opera.A. clappedB. laughedC. chattedD. contributed

单选题They are concerned for the fate of the forest and the Indians who dwell in it.

单选题I wasn't qualified for the job really but I got it anyhow. A. besides B. anyway C. well D. anymore

单选题The Origin of Language is a Mystery How men first learned to invent words is unknown; in other words, the origin of language is a mystery. All we really know is that men, unlike animals, somehow invented certain sounds to express thoughts and feelings, actions and things, so that they could communicate with each other; and that later they agreed upon certain signs, called letters, which could be combined to represent those sounds, and which could be written down. Those sounds, whether spoken, or written in letters we call words. The power of words, then, lies in their combinations—the things they bring up before our minds. Words become filled with meaning for us by experience; and the longer we live, the more certain words recall to us the glad and sad events of our past; and the more we read and learn, the more the number of words that mean something to us increases. Great writers are those who not only have great thoughts but also express these thoughts in words which appeal powerfully to our minds and feelings. This charming and telling use of words is what we call literary (文字的) style. Above all, the real poet is a master of words. He can convey his meaning in words which sing like music, and which by their position and association can move men to tears. We should therefore learn to choose our words carefully and use them accurately, or they will make our speech silly and rude.

单选题Some children have never seen a dentist before starting school.

单选题They became very tense during the Ucrucial/U stage of the experiment.

单选题Margaret Sanger and Birth Control Margaret Sanger, an American nurse, was the first to start the modem birth control movement in the United States. In 1912 she 31 publishing information about women"s reproductive (生殖的) concerns through articles and books. In 1914 Sanger was charged 32 violation of, the Comstock Law, which federal legislation had passed in 1873 forbidding the mailing of sexy material 33 information about birth control and contraceptive (避孕的) devices. Though she was put in jail for these activities, Sanger 34 to publish and spread information about birth control. She and her sister Ethel Byrne opened the first of several birth control clinics in America on October 16, 1916, in Brooklyn, New York. The Comstock Law was rewritten by Congress in 1936 to 35 birth control information and devices. Many states had laws forbidding distribution or use of contraceptive devices but the constitutionality (合宪性) of these laws was increasingly 36 In 1965, the Supreme Court of the United States ruled that married people have the right to practice birth control without government intervention. In 1972, the court 37 that unmarried people have the same right. Today there are more birth control options 38 , but overpopulation and unwanted pregnancies remain worldwide 39 . Having more children than one can support may lead 40 poverty, illness, and high death rates for babies, children, and women. The problem of teenage pregnancy is 41 worse in the United States 42 in almost any other developed country. Studies show that birth rates for women under 20 are higher in the United States than in 29 other 43 countries. A detailed study suggested that the problem of teenage pregnancy in the United States may be 44 to less sex education in schools and lower availability (可获性) of contraceptive services and supplies to young people. This study 45 the view of people in the United States who argue that sex education or making contraceptive supplies available to school-age children promotes sexual activity.

单选题Corporation Income Tax Business corporations, like individuals, must pay taxes on their income In 1966 the corporation income tax provided 23 percent of all government receipts. By 1983 the figure had dropped to 6.2 percent, but by 1987 it climbed to 10.2 percent. The corporation income tax is often criticized as double taxation(税收). Not only must the company pay taxes on its profits, but individual shareholders(股东) must also pay personal income taxes on dividend(红利) income. The small stockholder has been given some relief by the provision allowing taxpayers to deduct(扣除) the fist $100 they receive in dividends from their personal income. In addition, money that is gained from the increase in the value of stock sold at least six months after its purchase considered a capital gain. The law allows the seller of such stock to pay a lower tax tate on the capital gain. However, gains from stock owned for less than six months are taxed at the rate of regular income. Many business people have complained—probably with some justification—that high corporate taxes interfere with their opportunities to reinvest their profits in their businesses. Such interference can hinder(妨碍) the growth and modernization of businesses. Some industrial nations that have expanded rapidly in the last 15 years have far lower taxes on corportations than the United States does. Many economists believe that low corporation taxes have been a help in this business expansion. A corporation income tax is based on a corporation's annual income after it has paid its expenses. Dividends to stockholders are not included as expenses. Recent changes in the tax have reduced the rates in order to encourage business investment in research and new capital equipment. The new rates are more progressive, increasing from 15 percent on the first $25,000 of taxable income to 46 percent on all taxable income above $100,000. The incidence of the tax tends to fall on the stockholders in highly competitive business because shifting the tax to the consumer would raise prices and cut down on sales.

单选题Giving Up Smoking A number of devices are available to help a person quit smoking. Nicotine (尼古丁) patches are small, nicotine-containing adhesive (粘着性的) discs applied to the skin. The nicotine is slowly absorbed through the skin and enters the bloodstream (血流). Over time, the nicotine dose is reduced and eventually the desire for nicotine is eased. Nicotine gum (口香糖) works in a similar manner, providing small doses of nicotine when chewed (咀嚼). The benefits of giving up smoking include the immediate reduction of harm to the health of the smoker and easier admission to social activities and institutions that ban smoking. In a 1988 report, the U.S. Surgeon General declared cigarette smoking to be more harmful and expensive than the use of cocaine (可卡因), alcohol, or heroin. Recent evidence supports this claim. The United States government has collected a special tax on cigarettes for several decades. The rate rose from 8 cents per pack of 20 cigarettes in 1951 to 24 cents per pack in 1993. In other developed countries, the cigarette tax rate is much higher, ranging from 50 percent in Switzerland to 85 percent in Denmark. In the United States, the first direct action to check smoking was the regulation of a warning on cigarette packages by the Federal Trade Commission. This warning took effect in 1964 and was strengthened in 1969 to read: "Warning: The Surgeon General Has Determined That Cigarette Smoking Is Dangerous to Your Health." In 1971 all cigarette advertising was banned from radio and television, and cities and states passed laws requiring nonsmoking sections in public places and workplaces.

单选题Stem Cell Therapy May Help Repair the Heart According to scientists in the USA, stem cell therapy may one day be able to repair the hearts of people with heart failure. Researchers at Pittsburgh University School of Medicine examined 20 patients who had severe heart failure and were going to have surgery. They injected stem cells into the parts of their hearts that were damaged. They then compared their hearts with those of people who had undergone surgery without having the stem cells injected into them (they had also suffered from severe heart failure). The patients who had had the stem cells injected had hearts that were able to pump (用泵抽取) more blood than the others. According to Professor Robert Kormos, one of the researchers, these results could revolutionize heart treatment. Although previous studies had indicated that there might be a benefit, this is the first study that has actually proved that stem cell therapy can help the failing heart work better. All the patients in this study had hearts that could not pump blood properly. The scientists measured their ejection fraction (射血分数). It is a measure of heart performance; you measure how much blood is being pumped out by the left ventricle (心室). Healthy people"s ejection fraction is about 55%. These patients had ejection fraction of under 35%. They all had by-pass surgery (搭桥手术) performed on them. Some of the patients had stem cells taken from their hip bones and injected into 25—30 sites in the damaged heart muscle. Six months later their ejection fraction rate was 46.1% while those who just had surgery but no stem cell injections averaged 37.2%. No side effects were reported. Heart failure is a common problem all over the world. In the UK alone about 650,000 people suffer from heart failure every year. As the number of people suffering from heart failure increases in the world in general these findings are particularly significant. Current treatments relieve the symptoms. This new stem cell therapy actually repairs the damaged muscle in the heart and has the potential of curing the disease.

单选题Future Kitchen In a house, the kitchen is most likely to change in the future. The refrigerator may be able to talk to the owner when some part of it wears out. So before it stops working, the refrigerator itself" may let you know that there's a problem. In addition, your fridge will also be able to tell you what are inside it. You don't need to stand in front of an open refrigerator and look for what you want. When you have taken out the food from your refrigerator, your table may suggest recipes based on what you put on it. How is this possible? The reason is the tiny computer chips, called RFIDs. They will be put in all the equipment in your kitchen, and even in furniture. Besides refrigerator and table, other equipment in your kitchen will benefit you because of the chips. The washing machine will know how to wash plates cleaner. And you will be able to control your oven with your cell phone. You put your dinner into the oven before you leave home, and your phone will tell the oven when to start cooking, so that the meal has been ready when you get home. When you go to a grocery store, the RFIDs will also help you a lot. You put the chips in your shopping bag before leaving home, and then they wild tell you what you already have in your refrigerator. And the chips will charge your credit card, so that you don't need to wait for a long lime before the cash desk any more. If you love all the things today's kitchen can do for you, you'll love what tomorrow's kitchen will do for you.

单选题Human Heart Can Make New Cells Solving a longstanding mystery, scientists have found that the human heart continues to generate new cardiac cells throughout the life span, although the rate of new cell production slows with age. The finding, published in the April 3 issue of Science, could open a new path for the treatment of heart diseases such as heart failure and heart attack, experts say. "We find that the beating cells in the heart, cardiomyocytes, are renewed," said lead researcher Dr. Jonas Frisen, a professor of stem cell research at the Karolinska Institute in Stockholm, Sweden. "It has previously not been known whether we were limited to the cardiomyocytes we are born with or if they could be renewed," he said. The process of renewing these cells changes over time, Frisen added. In a 20-year-old, about 1 percent of cardiomyocytes are exchanged each year, but the turnover rate decreases with age to only 0.45 percent by age 75. "If we can understand how the generation of new cardiomyocytes is regulated, it may be potentially possible to develop pharmaceuticals that promote this process to stimulate regeneration after for example, a heart attack, "Frisen said. That could lead to treatment that helps restore damaged hearts. "A lot of people suffer from chronic heart failure," noted co-author Dr. Ratan Bhardwaj. Ratan Bhardwaj, also from the Karolinska Institute. "Chronic heart failure arises from heart cells dying," he said. With this finding, scientists are "opening the door to potential therapies to having ourselves heal ourselves," Bhardwaj said. "Maybe one could devise a pharmaceutical agent that would make heart cells make new and more cells to overcome the problem they are facing." But barriers remain. According to Bhardwaj, scientists do not yet know how to increase heart cell production to a rate that would replace cells faster than they are dying off, especially in older patients with heart failure. In addition, the number of new cells the heart produces was estimated using healthy hearts-whether the rate of cell turnover in diseased hearts is the same remains unknown.

单选题An Englishman invented the fridge in the 1920s.

单选题The reason why he adapted to the new situations quickly is that he has a flexible attitude.

单选题If many older physicians stop working in the coming years, Americans will have

单选题Sally likes to {{U}}tease{{/U}} her brother about his girl friends. A.charm B.laugh at C.criticize D.respect

单选题The Chemieals Within As an Alaskan fisherman, Timothy June, 54, used to think that he was safe from industrial pollutants at his home in Haines - a town with a population of 2,400 people and 4,000 eagles, with 20 million acres of protected wilderness nearby. But in early 2007, June agreed to take part in a survey of 35 Americans from seven states. It was a biomonitoring project, in which people' s blood and urine were tested for traces of chemicals - in this case, three potentially hazardous classes of compounds found in common household products like shampoo, tin cans, shower curtains and upholstery (椅子套). The results- released in November in a report called "Is It in Us?" by a coalition of environmental groups - were not reassuring. Every one of the participants, ranging from an Illinois state legislator to a Massachusetts minister, tested positive for all three classes of contaminants (污染物). And while the simple presence of these chemicals doesn' t necessarily indicate a health risk, the fact that typical Americans carry these chemicals at all shocked June and his fellow participants. As Stephanie Felten, 28, of Aurora, Ill. , put it, "Why should chemical companies be allowed to roll the dice on my health?" Clearly, there are chemicals in our bodies that don' t belong there. The Centers for Disease Control and Prevention conducts a large, ongoing survey that has found 148 chemicals in Americans of all ages, including lead, mercury (汞), dioxins and PCBs. Other scientists have detected antibacterial agents from liquid soaps in breast milk, infants' cord blood and the urine of young girls. And in 2005, the Environmental Working Group found an average of 200 chemicals in the cord blood of 10 newborns, including known carcinogens and neurotoxins. "Our babies are being born pre - polluted," says Sharyle Patton of Commonweal, which cosponsored "Is It in Us?" "This is going to be the next big environmental issue after climate change. /

单选题{{B}}第二篇{{/B}} Believe it or not,optical illusion (错觉) can cut highway crashes. Japan is a case in point. It has reduced automobile crashes on some roads by nearly 75 percent using a simple optical illusion. Bent stripes, called chevrons (人字形) painted on the roads make drivers think that they are driving faster than they really are, and thus drivers slow down. Now the American Association Foundation for Traffic Safety in Washington D. C. is planning to repeat Japan's success. Starting next year, the foundation will paint chevrons and other patterns of stripes on selected roads around the country to test how well the patterns reduce highway crashes. Excessive speed plays a major role in as much as one fifth of all fatal traffic accidents, according to the foundation. To help reduce those accidents, the foundation will conduct its tests in areas where speed-related hazards are the greatest--curves, exit slopes, traffic circles, and bridges. Some studies suggest that straight, horizontal bars painted across roads can initially cut the average speed of drivers in half. However, traffic often returns to full speed within months as drivers become used to seeing the painted bar. Chevrons, scientists say, not only give drivers the impression that they are driving faster than they really are but also make a lane spear to be narrower. The result is a longer lasting reduction in highway speed and the number of traffic accidents.

单选题Many cities have restricted smoking in public places.