单选题With immense relief, I stopped running. A. some B. enormous C. little D. extensive

单选题Putting Plants to Work Using the power of the sun is nothing new. People have had solar-powered calculators and buildings with solar panels for decades. But plants are the real experts: They've been using sunlight as an energy source for billions of years. Ceils in the green leaves of plants work like tiny factories to convert sunlight, carbon dioxide, and water into sugars and starches, stored energy that the plants can use. This conversion process is called photosynthesis. Unfortunately, unless you're a plant, it's difficult and expensive to convert sunlight into storable energy. That's why scientists are taking a closer look at exactly how plants do it. Some scientists are trying to get plants, or biological cells that act like plants, to work as miniature photosynthetic power stations. For example, Mafia Ghirardi of the National Renewable Energy Laboratory in Golden, Colo., is working with green algae. She's trying to trick them into producing hydrogen instead of sugars when they perform photosynthesis. Once the researchers can get the algae working efficiently, the hydrogen that they produce could be used to power fuel cells in cars or to generate electricity. The algae are grown in narrow-necked glass bottles to produce hydrogen in the lab during photosynthesis, plants normally make sugars or starches. "But under certain conditions, a lot of algae are able to use the sunlight energy not to store starch, but to make hydrogen." Ghirardi says. For example, algae will produce hydrogen in an air free environment. It's the oxygen in the air that prevents algae from making hydrogen most of the time. Working in an air free environment, however, is difficult. It's not a practical way to produce cheap energy. But Ghirardi and her colleagues have discovered that by removing a chemical called sulfate from the environment that the algae grow in, they will make hydrogen instead of sugars, even when air is present. Unfortunately, removing the sulfate also makes the algae's cells work very slowly, and not much hydrogen is produced. Still, the researchers see this as a first step in their goal to produce hydrogen efficiently from algae. With more work, they may be able to speed the cells' activity and produce larger quantities of hydrogen. The researchers hope that algae will one day be an easy-to-use fuel source. The organisms are cheap to get and to feed, Ghirardi says, and they can grow almost anywhere: "You can grow them in a reactor, in a pond You can grow them in the ocean. There's a lot of flexibility in how you can use these organisms. /

单选题Human Space Exploration While scientists are searching the cause of the Columbia disaster, NASA is moving ahead with plans to develop a new craft that would replace shuttles(航开飞机)on space station missions by 2012 and respond quickly to space station emergencies. The space agency released the first set of mission needs and requirements several days ago for me orbital space plane(轨道航天飞机), which would be designed to transport a crew of four to and from the International Space Station. Although it includes few specifics, the plan states the orbiter(轨道航天飞机)will be safer cheaper and require less preparation time than the shuttle. It would be able to transport four crew members by 2012--though it would be available for rescue missions by 2010 NASA says the craft should be able to transport injured or ill space station crew- members to "definitive(决定性的) medical care" within 24 hours. The release of the requirements showed NASA remains focused on the long-term priorities of space exploration, even as questions exist concerning the loss of Columbia and its seven, member crew- on February 1, 2003. Expels at Marshall Space Flight Center in Huntsville, Alabama, have been working for years on a successor to the shuttle. The project, known as the Space Launch Initiative(倡议), was divided last year into two parts----one focusing on a future launch vehicle, the other on a space station orbiter. The orbiter is expected to be ready sooner. The program's managers say NASA officials have told them not to alter Space Launch Initiative in light of the Columbia disaster. U. S. President George W: Bush asked Congress for about US$1 billion for Space Launch Initiative in 2004, funds that would be almost equally split between the Orbital Space Plane and Next Generation Launch Technology.

单选题Teaching Math, Teaching Anxiety In a new study about the way kids learn math in elementary school, the psychologists at the University of Chicagol Sian Beilock and Susan Levine found a surprising relationship between what female teachers think and what female students learn: If a female teacher is uncomfortable with her own math skills, then her female students are more likely to believe that boys are better than girls at math. "If these girls keep getting math-anxious female teachers in later grades, it may create a snowball effect on their math achievement," said Levine. In other words, girls may end up learning math anxiety from their teachers. The study suggests that if these girls grow up believing that boys are better at math than girls are, then these girls may not do as well as they would have if they were more confident. Just as students find certain subjects to be difficult, teachers can find certain subjects to be difficult to learn—and teach. The subject of math can be particularly difficult for everyone. Researchers use the word "anxiety" to describe such feelings: anxiety is uneasiness or worry. The new study found that when a teacher has anxiety about math, that feeling can influence how her female students feel about math. The study involved 65 girls, 52 boys and 17 first-and second-grade teachers in elementary schools in the Midwest. The students took math achievement tests at the beginning and end of the school year, and the researchers compared the scores. The researchers also gave the students tests to tell whether the students believed that a math superstar had to be a boy. Then the researchers turned to the teachers: To find out which teachers were anxious about math, the researchers asked the teachers how they felt at times when they came across math, such as when reading a sales receipt. A teacher who got nervous looking at the numbers on a sales receipt, for example, was probably anxious about math. Boys, on average, were unaffected by a teacher's anxiety. On average, girls with math- anxious teachers scored lower on the end-of-the-year math tests than other girls in the study did. Plus, on the test showing whether someone thought a math superstar had to be a boy, 20 girls showed feeling that boys would be better at math—and all of these girls had been taught by female teachers who had math anxiety. "This is an interesting study, but the results need to be interpreted as preliminary and in need of replication with a larger sample," said David Geary, a psychologist at the University of Missouri in Columbia.

单选题"Salty" Rice Plant Boosts Harvests British scientists are breeding a new generation of rice plants that will be able to grow in soil containing salt water. Their work may enable abandoned farms to become productive once more. Tim Flowers and Tony Yeo, from Sussex University"s School of Biological Sciences, have spent several years researching how crops, such as rice, could be made to grow in water that has become salty. The pair have recently begun a three-year programme, funded by the Biotechnology and Biological Sciences Research Council, to establish which genes enable some plants to survive salty conditions. The aim is to breed this capability into crops, starting with rice. It is estimated that each year more than 10m hectares (公顷) of agricultural land are lost because salt gets into the soil and stunts (妨碍生长) plants. The problem is caused by several factors. In the tropics, mangroves (红树林) that create swamps (沼泽) and traditionally formed barriers to sea water have been cut down. In the Mediterranean, a series of droughts have caused the water table to drop, allowing sea water to seep (渗透) in. In Latin America, irrigation often causes problems when water is evaporated (蒸发) by the heat, leaving salt deposits behind. Excess salt then enters the plants and prevents them functioning normally. Heavy concentrations of minerals in the plants stop them drawing up the water they need to survive. To overcome these problems, Flowers and Yeo decided to breed rice plants that take in very little salt and store what they do absorb in cells that do not affect the plants" growth. They have started to breed these characteristics into a new rice crop, but it will take about eight harvests before the resulting seeds are ready to be considered for commercial use. Once the characteristics for surviving salty soil are known, Flowers and Yeo will try to breed the appropriate genes into all manners of crops and plants. Land that has been abandoned to nature will then be able to bloom again, providing much needed food in the poorer countries of the world.

单选题The chemical is {{U}}deadly{{/U}} to rats but safe to cattle. A. fatal B. hateful C. good D. useful

单选题{{U}}On behalf of{{/U}} everyone in this party, I wish you a very happy birthday.

单选题This tape-recorder has a tape-slide {{U}}facility{{/U}}.

单选题I hope that I didn't do anything absurd last night. A. awkward B. strange C. stupid D. awful

单选题We have thought varied ways to handle the problemA. sameB. differentC. manyD. few

单选题Which of the following about the ladle shaped compass is true?

单选题What does fossil and molecular evidence tell us about our earliest ancestors?

单选题{{B}}第三篇{{/B}} Electronic Teaching The potential of closed-circuit television and other new electronic teaching tools is so great that it is fascinating to visualize "the school of tomorrow". Televised lessons will originate from a central building having perhaps four or five master studios. The lessons will be carried into classrooms all over a city, or even an entire country. After a televised lesson has been given, the classroom teacher will take over for the all important "follow-up" period. The students will ask any troublesome questions, and difficult points will be cleared up through discussion. The teacher in the classroom will have additional electronic tools. On the teacher's desk, the traditional chalk and erasers will have been replaced by a multiple-control panel and magnetic tape player. The tape machines will run pre recorded lessons which pupils will follow by headphones. The lessons will be specifically geared to the students' levels of ability. For instance, while the class as a whole studies history, each student will receive an individual history lesson, directed to his particular level of ability. Should question arise, the students will be able to talk directly to the teacher on individual "intercoms" without disturbing the rest of the class. In this way, the teacher will be able to conduct as many as three classes at the same time. With the rapid development of computer science, students will be aided with specially prepared multimedia software to study their subjects better. Homework will possibly be assigned and handed in via electronic mail system. Students can even take examinations on their computer linked with the teacher's and get the score instantly. They will get certificates or diplomas if they pass all the required examinations. Experts believe that this type of education will be very popular in the years ahead.

单选题The reason for their unusual behavior remains a Upuzzle/U.

单选题Please put up your hands if you have any questions.

单选题We bad a long Uconversation/U about her parents.

单选题He Uinspired /U many young people to take up the sport

单选题 下面的短文后列出了7个句子，请根据短文的内容对每个句子作出判断；如果该句提的是正确信息，请选择A；如果该句提的是错误信息，请选择B；如果该句的信息文中没有提及，请选择C。 Tokyo is World's Priciest City The weak American dollar and strong European and Asian currencies helped make Tokyo and London the most expensive cities in the world, according to a recent survey. American cities were absent from the top 10, with the most expensive U. S. city, New York, dropping two spots from last year to 12 in the survey of 144 urban areas conducted by Mercer Human Resource Consulting. Moscow ranked in third place, with Osaka, and Hong Kong rounding out the top five most expensive cities. The survey, drawn up twice a year, ranks cost of living for foreign workers, not local residents, and is used primarily by multinational companies to determine pay for expatriate employees. "The euro appreciated (升值) more than 11 percent in the last six months. " said Marie-Laurence Sepede, senior researcher at Mercer. "So that made European cities go up and U.S. cities drop. " Sepede noted that while U.S. cities got cheaper in relation to those in Europe and Asia, the rankings among: American cities remained similar to previous years, with Los Angeles, Chicago and San Francisco all placing high on the list. Also not able was the climb of Australian and New Zealand cities up the list, a shift caused by those nation's strong currencies. Sydney moved from 67 last year to 20 this year, and Auckland, New Zealand climbed 35 places to 80. The rest of the top 20 remained fairly constant, although Paris, Vienna, Austria and Istanbul, Turkey made their first appearances so high in the rankings. The survey took into consideration 250 criteria, including the cost of utilities, food and entertainment. While the survey looked at a range of living standards, Sepede said the study was most representative of the expenses of people working for big international corporations and maintaining fairly high standards of living. Mercer said the continued appreciation of the euro against the U. S. dollar could eventually force companies to move employees and reorganize. "Mainly, the depreciation(贬值) of the dollar makes it cheaper to send employees to American cities," said Jackie Barber, a spokeswoman for the survey.

单选题Her novel {{U}}depicts{{/U}} an ambitious Chinese.

单选题The novel depicts the history of the nation. A. narrates B. illustrates C. describes D. exemplify