单选题Gooseneck barnacles attach themselves to objects such as docks and boats.

单选题Ten years after the event,her death still remains a puzzle. A. mist B. fog C. secret D. mystery

单选题When doves are about two weeks old, they are Covered with grey feathers and are ready to Utry/U their wings.

单选题Arctic Melt Earth's North and South Poles are famous for being cold and icy. Last year, however, the amount of ice in the Arctic Ocean fell to a record low. Normally, ice builds in Arctic waters around the North Pole each winter and shrinks during the summer. But for many years, the amount of ice left by the end of summer has been declining. Since 1979, each decade has seen an 11.4 percent drop in end of summer ice cover. Between 1981 and 2000, ice in the Arctic lost 22 percent of its thickness, becoming 1.13 meters thinner. Last summer, Arctic sea ice reached its skimpiest levels yet. By the end of summer 2007, the ice had shrunk to cover just 4.2 million square kilometers. That's 38 percent less area than the average cover at that time of year. And it's a very large 23 percent below the previous record low, which was set just 2 years ago. This continuing trend has scientists concerned. There may be several reasons for the ice melt, says Jinlun Zhang, an oceanographer at the University of Washington at Seattle. Unusually strong winds blew through the Arctic last summer. The winds pushed much of the ice out of the central Arctic, leaving a large area of thin ice and open water. Scientists also suspect that fewer clouds cover the Arctic now than in the past. Clearer skies allow more sunlight to reach the ocean. The extra heat warms both the water and the atmosphere. In parts of the Arctic Ocean last year, surface temperatures were 3.5℃ warmer than average and 1.5℃ warmer than the previous record high. With both air and water getting warmer, the ice is melting from both above and below. In some parts of the Beaufort Sea, north of Alaska and western Canada, ice that measured 3.3 meters thick at the beginning of the summer measured just 50 centimeters by season's end. The new measurements suggest that melting is far more severe than scientists have seen by just looking at ice cover from above, says Donald K. Perovich, a geophysicist at the U. S. Army Cold Regions Research and Engineering Laboratory in Hanover, N. H. Some scientists fear that the Arctic is stuck in a warming trend from which it may never recover.

单选题During the past ten years there have been dramatic changes in the international situation.

单选题In arithmetic, a number {{U}}stands for{{/U}} the size of a set of things.

单选题The policemen acted quickly because lives were at stake A．in danger B．in diffculty C．in despair D．out of control

单选题______ recent developments we do not think your scheme is practical.A. In view ofB. In favor ofC. In case ofD. In memory of

单选题Medical facilities are being{{U}} upgraded{{/U}}．

单选题it is possible to approach the problem in a different way.A. handleB. raiseC. poseD. experience

单选题Halloween Halloween is an autumn holiday that Americans celebrate every year. It means "holy evening", and it comes every October 31, the evening before All-Saints Day. It used to be thought the most wonderful night of the year. It was the night when witches and evil spirits came back on earth. People kept up many strange old customs in an effort to keep these evil things away. Farmers used to light big fires in their fields, and the farm workers and their families would walk around the fields singing old songs. Sometimes they would stop to hear the local priest offer prayers to the good spirits, and ask them to help keep the evil ones away. Great care was taken that none of the farm animals were left in the fields. They would all be locked up safely in their stables, and over each of the stable doors a few rowan leaves would be hung. Witches and evil spirits would not go anywhere near the rowan tree. In more recent times, Halloween has become a time for the parties, when children dress up as witches and play all kinds of special games. After the games there is often a big supper with plenty of pumpkin pie, cakes and a lot of other delicious things to eat. But for the most part the children enjoy the fun of dressing up and playing their favorite game of "Trick or Treat". They run down each street knocking on the doors crying loudly "Trick or Treat! Money or eat!", and most people have some sweets or money ready to give them. Those that do not can expect maybe to have a tyre flattened, or their windows covered in soap. Or the children may just knock on the door and run away. Some children think of other people on Halloween. They carry boxes for UNICEF (The United Nations International Children's Emergency Fund). They ask for money to help poor children all around the world. Of course, every time they help UNICEF, they usually receive a treat for themselves, too. Every autumn, when the vegetables are ready to eat, children pick large orange pumpkins. Then they cut faces in the pumpkins and put lights inside. It looks like there is a person looking out of the pumpkin! These lights are called jack-o'-lanterns, which means "Jack of the lantern". But in this modern age many of the pumpkins are being replaced with plastic electric ones that can be brought out each year.

单选题I stroll around the park for an hour after dinner every day.

单选题Gambling is Ulawful/U in Nevada.

单选题If wool is submerged in hot water, it tends to shrink.

单选题John doesn't believe in traditional medicine; he has some remedies of his own.A. correctB. regularC. commonD. conventional

单选题When We Are Asleep Everyone dreams, but some people never recall their dreams, or do so very rarely. Other people always wake up with vivid recollections (记忆) of their dreams, though they forget them very quickly. In an average night of eight hours' sleep, an average adult will dream for around one hundred minutes, probably having three to five dreams, each lasting from ten to thirty minutes. Scientists can detect when someone is having a dream by using an instrument which measures the electrical waves in the brain. During dreaming, these waves move more quickly. Breathing and pulse rate also increase, and there are rapid eye movements under the lids, just as though the dreamer were really looking at moving objects. These signs of dreaming have been detected in all mammals (哺乳动物) studied, including dogs, monkeys, cats, and elephants, and also some birds and reptiles (爬行动物). This period of sleep is called the "D" state. Babies experience the "D" state for around 50% of their sleep; the period reduces to around 25% by the age of 10. Dreams take the form of stories, but they may be strange and with incidents not connected, which make little sense. Dreams are seldom without people in them and they are usually about people we know. One estimate says that two-thirds of the "cast" of our dream dramas are friends and relations. Vision seems an essential part of dreams, except for people blind from birth. Sound and touch are senses also often aroused, but smell and taste are not frequently involved. In "normal" dreams, the dreamer may be taking part, or be only an observer. But he or she cannot control what happens in the dream. However, the dreamer does have control over one type of dream. This type of dream is called a "lucid" (清醒的) dream. Not everyone is a lucid dreamer. Some people are occasional lucid dreamers. Others can dream lucidly more or less all the time. In a lucid dream, the dreamer knows that he is dreaming.

单选题 Students Learn Better with Touchscreen Desks Observe the criticisms of nearly any major public education system in the world, and a few of the many complaints are more or less universal. Technology moves faster than the education system. Teachers must teach at the pace of the slowest student rather than the fastest. And—particularly in the United States—grade school children as a group don't care much for, or excel at, mathematics. So it's heartening to learn that a new kind of "classroom of the future" shows promise at mitigating some of these problems, starting with that fundamental piece of classroom furniture: the desk. AUK study involving roughly 400 students, mostly aged 8-10 years, and a new generation of multi- touch, multi-user, computerized desktop surfaces is showing that over the last three years the technology has appreciably boosted students' math skills compared to peers learning the same material via the conventional paper-and-pencil method. How? Through collaboration, mostly, as well as by giving teachers better tools by which to micromanage individual students who need some extra instruction while allowing the rest of the class to continue moving forward. Science, Clay Dillow, classroom of the future, education, engineering, math, mathematics, Synergy Net Traditional instruction still shows respectable efficacy at increasing students fluency in mathematics, essentially through memorization and practice—dull, repetitive practice. But the researchers have concluded that these new touch screen desks boost both fluency and flexibility—the critical thinking skills that allow students to solve complex problems not simply through knowing formulas and devices, but by being able to figure out what there all problem is and the most effective means of stripping it down and solving it. One reason for this, the researchers say, is the multi-touch aspect of the technology. Students working in the next-gen classroom can work together at the same tabletop, each of them contributing and engaging with the problem as part of a group. Known as Synergy Net, the software uses computer vision systems that see in the infrared spectrum to distinguish between different touches on different parts of the surface, allowing students to access and use tools on the screen, move objects and visual aids around on their desktops, and otherwise physically interact with the numbers and information on their screens. By using these screens collaboratively, the researchers say, the students are to some extent teaching themselves as those with a stronger grasp on difficult concepts pull other students forward along with them.

单选题Rise in Number of Cancer Survivors Cancer is the second leading cause of death in the United States, after heart disease. In the 1 , it was often considered a death sentence. But many patients now live longer 2 of improvements in discovery and treatment. Researchers say death 3 in the United States from all cancers combined have fallen for thirty years. Survival rates have increased for most of the top fifteen cancers in both men and women, and for cancers in 4 . The National Cancer Institute and the Centers for Disease Control and Prevention studied the number of cancer survivors. A cancer survivor is defined 5 anyone who has been found to have cancer. This would include current patients. The study covered the period 6 1971 to 2001. The researchers found there are three 7 as many cancer survivors today as there were thirty years ago. In 1971, the United States had about three-million cancer 8 . Today there are about ten-million. The study also found that 64% of adults with cancer can expect to still be 9 in five years. Thirty years ago, the five-year survival rate was 50%. The government wants to 10 the five-year survival rate to 70% by 2010. The risk of cancer increases with age. The report says the majority of survivors are 65 years and 11 . But it says medical improvements have also helped children with cancer live 12 longer. Researchers say 80% of children with cancer will survive at least five years after the discovery. About 75% will survive at 13 ten years. In the 1970s, the five-year survival rate for children was about 50%. In the 1960s, most children did not survive cancer. Researchers say they 14 more improvements in cancer treatment in the future. In fact, they say traditional cancer-prevention programs are not enough anymore. They say public health programs should also aim to support the 15 numbers of cancer survivors and their families.

单选题He talks tough but has a tender heart.

单选题The Now Rich and the Old Rich Though it is mere 1 to 3 percent of the population, the upper class possesses at least 25 percent of the nation"s wealth. This class has two segments: upper-upper and lower-upper. Basically, the upper-upper class is the "old rich"—families that have been wealthy for several generations and aristocracy of birth and wealth. Their names are in the Social Register, a listing of acceptable members of high society. A few are known across the nation, such as the Rockfellers, Roosevelts, and Vanderbilts. Most are not visible to the general public. They live in grand seclusion (深居简出), drawing their income from the investment of their inherited wealth. In contrast, the lower-upper class is the "new rich". Although they may be wealthier than some of the old rich, the new rich have hustled (急于做) to make their money like everybody else beneath their class. Thus their prestige is generally lower than that of the old rich, who have not found it necessary to lift a finger to make their money, and who tend to look down upon the new rich. However its wealth is acquired, the upper class is very, very rich. They have enough money and leisure time to cultivate an interest in the arts and to collect rare hooks, painting, and sculpture. They generally live in exclusive areas, belong to exclusive social clubs, communicate with each other, and marry their own kind—all of which keeps them so distant from the masses that they have been called the out-of-sight class. They also command an enormous amount of power and influence here and abroad, as they hold many top government positions, run the Council on foreign relations, and control multinational corporations. Their actions affect the lives of millions.