单选题The word ―sustainable in the last paragraph is closest in meaning to __________ .

单选题Shelly had prepared carefully for her biology examination so that she could be sure of passing it on her first endeavor .

单选题Who absorb low-level radiation at a higher rate than the others?

单选题We have made a try to boost participation in the program, but it failed.A. attemptB. effortC. energyD. source

单选题阅读下面的短文，文中有15处空白，每处空白给出4个选项，请根据短文的内容从4个选项中选择1个最佳答案。 In 1980 a report was published about what the earth might be like 20 years from then. The report was the result of a three-year study. According to the report, the picture of the earth in the year 2,000 is not a{{U}} (51) {{/U}}one. The world will be more crowded because the{{U}} (52) {{/U}}will continue to grow. The population{{U}} (53) {{/U}}be as large as 6,300 million, almost 2,500 million more than that in 1975.{{U}} (54) {{/U}}people would move into cities, especially cities in{{U}} (55) {{/U}}countries. Cities like Cairo and Jakanta{{U}} (56) {{/U}}would each have 15 million by 'then. Food production will increase, but not enough to feed all the people. Farmers will grow 90 % more food than they did in 1975, but most of the increase would be in countries that already produce enough food for their people.{{U}} (57) {{/U}}increase is grown in South Asia, Africa and European countries. Poor farming ways are{{U}} (58) {{/U}}large areas of cropland, changing farms into deserts. More farmland is lost{{U}} (59) {{/U}}cities become larger and houses are built. Air pollution will get worse as industrial countries{{U}} (60) {{/U}}more coal and oil. Much of the world's{{U}} (61) {{/U}}could disappear as more and more trees are cut down. Energy will continue to be a{{U}} (62) {{/U}}problem. The experts hope their picture of the earth for the year 2000may be wrong. Measures must be taken to change the situation that{{U}} (63) {{/U}}today. By changing the situation, by setting the problems, the picture can be changed. There is{{U}} (64) {{/U}}time for the nations of the world to work together on a plan of action. But they{{U}} (65) {{/U}}that waiting too long to make decisions would greatly reduce the chances of success.

单选题It doesn"t stand to reason that he would lie.

单选题Dumped waste might contaminate water supplies.

单选题I have no alternative but to report him to the local police.

单选题Across the English Channel To swim across the English Channel takes at least nine hours. It's a hard work and it makes you short of breath. To fly over the Channel takes only twenty minutes (as only as you're not held up at the airport), but it's an expensive way to travel. You can travel by hovercraft if you don't mind the noise, and that takes forty minutes. Otherwise you can go by boat, if you dreams of being able to drive to France in his own car. "Not possible", you say. Well wait a minute. People are once again considering the idea of a Channel tunnel or bridge. This time, the Greater London Council is looking into the possibility of building a Channel link straight to London. A bridge would cost far more than a tunnel, but you would be able to go by rail or by car on a bridge, whereas a tunnel would provide a rail link only. Why is this idea being discussed again? Is Britain becoming more conscious of the need for links with Europe as a result of joining the EEC (欧共体)? Well, perhaps. The main reason, though, is that a tunnel or bridge would reach the twenty square kilometers of London's disused dockland(船坞地). A link from London to the continent would stimulate trade and re-vitalize(使…重新具有活力)the port, and would make London a main trading center in Europe. With a link over the Channel, you could buy your fish and chips in England and be able to eat them in France while they were still warm!

单选题Save Energy At Home On the average, Americans waste as much energy as two-thirds of the world"s population consumes. That"s largely the 1 of driving inefficient cars, using inefficient appliances (设备), and living and working in poorly insulated (隔热) buildings. Then what can you do to 2 the situation? Buy energy-efficient products—buy new appliances or electronics of the highest energy-efficiency rating. New energy-efficient models may cost more initially but have a lower operating 3 over their lifetimes, The most energy-efficient models 4 the Energy Star label, which identifies products 5 use 20-40 percent less energy than standard new products. According to the EPA (美国环境保护署), the typical American household can save about $400 per year in 6 bills with products that carry the Energy Star. Switch to compact fluorescent bulbs (荧光灯)—change the three bulbs you use 7 in your house to compact fluorescents. Each compact fluorescent bulb will keep half a ton of CO 2 out of the air 8 its lifetime, 9 , compact fluorescent bulbs last ten times as long and can save $30 per year in electricity costs. Set heating and cooling temperatures correctly-check thermostats (温度自动调节器) in your home to make sure they are 10 at a level that doesn"t waste energy. Turn off the lights—turn off lights and other electrical appliances such as televisions and radios when you"re not 11 them. Install automatic timers for lights that people in your house frequently 12 to turn them off when leaving a room. Let the sun shine in—the cheapest and most energy-efficient light and heat source is often right outside your window. On 13 days, open blinds (百叶窗) to let the sun light your home for free. Also remember that 14 entering a room equals passive solar heating. Even on cold winter days, sun streaming into a room can raise the temperature by several 15 .

单选题{{B}}第三篇{{/B}} If the salinity(含盐量) of ocean waters is analyzed, it is round to vary only slightly from place to place. Nevertheless, some of these small changes are important. There are three basic processes that cause a change in oceanic salinity. One of these is the subtraction of water from the ocean by means of evaporation—conversion of liquid water to water vapor. In this manner, the salinity is increased, since the sales stay behind. If this is carried to the extreme, of course, white crystals of salt would be left behind; this, by the way, is how much of the table salt we use is actually obtained. The opposite of evaporation is precipitation, such as rain, by which water is added to the ocean. Here the ocean is being diluted so that the salinity is decreased. This may occur in areas of high rainfall or in coastal regions where rivers flow into the ocean. Thus salinity may be increased by the subtraction of water by evaporation, or decreased by the addition of fresh water by precipitation or runoff. Normally, in tropical regions where the sun is very strong, the ocean salinity is somewhat higher than it is in other parts of the world where there is not as much evaporation. Similarly, in coastal regions where rivers dilute the sea, salinity is somewhat lower than in other oceanic areas. A third process by which salinity may be altered is associated with the formation and melting of sea ice. When seawater is frozen, the dissolved materials are left behind. In this manner, seawater directly beneath freshly formed sea ice has a higher salinity than it did before the ice appeared. Of course, when this ice melts, it will tend to decrease the salinity of the surrounding water. In the Weddell Sea, off Antarctica, the densest water in the oceans is formed as a result of this freezing process, which increases the salinity of cold water. This heavy water sinks and is found in the deeper portions of the oceans of the world.

单选题Clone Farm Factory farming could soon enter a new era of mass production. Companies in the US are developing the technology needed to "clone" chickens on a massive scale, once a chicken with desirable traits has been bred or genetically engineered, tens of thousands of eggs, which will hatch into identical copies, could roll off the production lines every hour. Billions of clones could he produced each year to supply chicken farms with birds that all grow at the same rate, have the same amount of meat and taste the same. This, at least, is the vision of the US's National Institute of Science and Technology, which has given Origen Therapeutics of Burlingame, California, and Embrex of North Carolina $ 4. 7 million to help fund research. The prospect has alarmed animal welfare groups, who fear it could increase the suffering of farm birds. That's unlikely to put off the poultry industry, however, which wants disease resistant birds that grow faster on less food. "Producers would like the same meat quantity but to use reduced inputs to get there, " says Mike Fitzgerald of Origen. To meet this demand, Origen aims to "create an animal that is effectively a clone", he says. Normal cloning doesn't work in birds because eggs can't be removed and implanted, Instead, the company is trying to bulkgrow embryonic stem cells taken from fertilized eggs as soon as they're laid. "The trick is to culture the cells without them starting to distinguish, so they remain pluripotent, " says Fitzgerald. Using a long-established technique, these donor cells will then be injected into the embryo of a freshly laid, fertilized recipient egg, forming a chick that is a "chimera". Strictly speaking a chimera isn't a clone, because it contains cells from both donor and recipient. But Fitzgerald says it will be enough if, say, 95 percent of a chicken's body develops from donor cells. "In the poultry world, it doesn't matter if it's not 100 percent, " he says. Another challenge for Origen is to scale up production. To do this, it has teamed up with Embrex, which produces machines that can inject vaccines into up to 50, 000 eggs an hour. Embrex is now trying to modify the machines to locate the embryo and inject the cells into precisely the right spot without killing it. In future, Origen imagines freezing stem cells from different strains of chicken. If orders come in for a particular strain, millions of eggs could be produced in months or even weeks. At present, maintaining all the varieties the market might call for is too expensive for breeders, and it takes years to bread enough chickens to produce the billions of eggs that farmers need.

单选题The orangutan Among all the animals, the ape is most like human beings. Both people and apes have the similar brain structure, the similar nerve system, and the similar kind of blood. There are four kinds of apes: the chimpanzee (黑猩猩), the orangutan (猩猩), the gorilla (大猩猩), and the gibbon (长臂猿). They live in the deep forests and warm tropical regions of Africa and of Southeast Asia, including Indonesia. All apes are covered with brown, reddish-brown, or black hair everywhere on their bodies except their faces, feet, and hands. Their hands each have four fingers and a thumb that helps them grip things the way our thumbs help us. But they also have a thumb on each foot instead of a big toe. Thus they can hold things with their feet also. Having short, weak legs, apes do not walk on the ground very much. However, their arms are very strong. This enables them to swing from branches and travel very quickly from tree to tree. These animals live in small family groups that move from place to place in search of vegetables and fruits. They also eat eggs, small animals, nuts, and insects. When they are tired, they build nests in the trees. But they rarely sleep there for more than a night or two. Then they move on to look for more food. There are some differences among the following three kids of apes. The gibbon is never more than three feet high and weight only about fourteen pounds. The gorilla grows to be six feet tall and weight up to 600 pounds. The orangutan is smaller than the gorilla. It stands three to five feet tall and weight up to 200 pounds. Chimpanzees are the smartest of all apes. They can be taught to sit at a table and eat, to dress themselves, and to do things that human children can do.

单选题Of all the planets in this solar system, Mercury is {{U}}nearest{{/U}} the Sun. A. most like B. closest to C. hotter than D. heavier than

单选题The ice is not thick enough to {{U}}bear{{/U}} the weigh of a tank．

单选题 阅读下面这篇短文，短文后有2项测试任务：(1)第23～26题要求从所给的6个选项中为第2～5段每段选择1个正确的小标题；(2)第27～30题要求从所给的6个选项中选择4个正确选项，分别完成每个句子。 {{B}}Attention to the Details{{/B}}1．Attention to detail is something everyone can and should do-- especially in a tight job market. Bob Crossley, a human-resources expert notices this in the job applications that come across his desk every day. "It's amazing how many candidates eliminate themselves ," he says.2．"Resumes(简历)arrive with stains. Some candidates don't bother to spell the company's name correctly. Once I see a mistake, I eliminate the candidate, "Crossley concludes. "if they cannot take care of these details, why should we trust them with a job?"3．Can we pay too much attention to details? Absolutely. Perfectionists struggle over little things at the cost of something larger they work toward. "To keep from losing the forest for the trees, "says Charles Garfield, associate professor at the University of California, San Francisco, "we must constantly ask ourselves how the details we're working on fit into the larger picture. If they don't we should drop them and move to something else."4．Garfield compares this process to his work as a computer scientist at NASA. "The Apollo moon launch was slightly off-course 90 percent of the time." says Garfield. "But a successful landing was still likely because we knew the exact 'coordinates of our goal. This allowed us to make adjustments as necessary. "Knowing where we want to go helps us judge the importance of every task we undertake.5．Too often we believe what accounts for others' success is some special secret or a lucky break (机遇). But rarely is success so mysterious. Again and again, we see that by doing little things within our grasp well, large rewards follow.

单选题Before the development of movable metal type in the mid-fifteen century, news was disseminated by word of mouth, by letter, or by public notice.

单选题The Taconic Mountains form part of the {{U}}dividing line{{/U}} between New York and Massachusetts.

单选题Before the first Apollo rocket went to the Moon, a spot for landing the lunar module was carefully chosen.

单选题He purchased this stamp at an auction.A. boughtB. showedC. tookD. made