单选题A3XX will fly faster while consuming less oil.

单选题France"s renewal of the nuclear testing in the South Pacific last month triggered political debates and mass demonstration.

单选题Her behaviour is extremely childish .

单选题The weather is a constant {{U}}subject {{/U}} of conversation in Britain.

单选题Customers often {{U}}defer{{/U}} payment as long as possible.

单选题 Pop Music in Africa Young musicians in African countries are creating a new kind of pop music. The tunes and the rhythms of their music combine African traditions with various forms of music popular today, such as hip-hop, rap, rock, jazz or reggae. The result is music that may sound familiar to listeners anywhere in the world, but at the same time is distinctly African. It is different also in another way- Many of the songs are very serious and they deal with important social or political issues in Africa today. Eric Wainaina is one of these African musicians. He grew up in Nairobi, Kenya, in a family of musicians. As a teenager, he listened to pop music from the United States, and later he moved to Boston to study at the Berklee College of Music. Now he has produced a CD in Kenya. Eric's most popular song, "Land of 'A Little Something' " is about Kenya's problem of bribery, or paying others for illegal favors. He wants people to listen to his songs and think about how to make Kenya a better place to live. Another musician who writes serious songs is Witness Mwaijaga from Tanzania. Her own experiences have helped her understand the suffering of many African women. At the age of fifteen she lost her home, but she was luckier than other homeless young people. She could make a living by writing songs and singing on the street. By the time she was eighteen years old, she had become a star. Her songs are written in rap or hip-hop style about the problems that she sees in Tanzania, especially AIDS and the lack of rights for women. Baaba Maal, from Senegal, also feels that pop music must go beyond entertainment. He says that in Senegal, storytellers have always been important people. In the past, they were the ones who kept the history of their people alive. Baaba believes that songwriters now have a similar responsibility. They must write about the world around them and help people understand how it could be better. The words of his songs are important, in fact. They speak of peace and cooperation among Africans, as well as the rights of women, love for one's family, and saving the environment. One of South Africa's most popular musicians is Brenda Fassie. She is sometimes compared to Madonna, the American pop star, because she likes to shock people in her shows. But she also likes to make people think. She became famous in the 1980s for her simple pop songs against apartheid. Now that apartheid has ended, her songs are about other issues in South African culture and life. To sing about these, she uses local African languages and a new pop style called kwaito. In recent years, people outside of Africa have also begun to listen to these young musicians. Through music, the younger generation of Africans are connecting with the rest of the world and, at the same time, influencing the rest of the world.

单选题The soldier displayed remarkable courage in the battle.

单选题Pendulums are used to regulate motion in some scientific {{U}}equipments{{/U}}.

单选题He is in a rather difficult {{U}}situation{{/U}} at present.

单选题While some office jobs would seem boring to many people, there are quite a few jobs that are stimulating, exciting and satisfying.A. hostileB. tediousC. fantasticD. courageous

单选题Thousands of people perished in the storm.

单选题I don't why everything around me is going into confusion.A. considerationB. puzzleC. attractionD. contradiction

单选题While he was in prison, his guards Udeprived/U him of all luxuries.

单选题A Phone That Knows You"re Busy It"s a modern problem: you"re too busy to be disturbed by incessant (连续不断的) phone calls so you turn your cell phone off. But if you don"t remember to turn it back on when you"re less busy. You could miss some important calls if only the phone knew when it was wise to interrupt you, you wouldn"t have to turn it off at all. Instead, it could let calls through when you are not too busy. A bunch of behavior sensors (传感器) and a clever piece of software could do just that, by analyzing your behavior to determine if it"s a good time to interrupt you. If built into a phone, the system may decide you"re too busy and ask the caller to leave a message or ring back later. James Fogarty and Scott Hudson at Camegie Mellon University in Pennsylvania based their system oil tiny microphones, cameras and touch sensors that reveal body language and activity. First they had to study different behaviors to find out which ones strongly predict whether your mind is interrupted. The potential "busyness" signals they focused on included whether the office doors were left open or closed, the time of day, if other people were with the person in question, how close they were to each other, and whether or not the computer was in use. The sensors monitored these and many other factors while four subjects were at work. At random intervals, the subjects rated how interruptible they were on a scale ranging from "highly interruptible" to "highly not-interruptible". Their ratings were then correlated with the various behaviors. "It is a shotgun (随意的) approach: we used all the indicators we could think of and then let statistics find out which were important," says Hudson. The model showed that using the keyboard, and talking on a landline or to someone else in the office correlated most strongly with how interruptible the subjects judged themselves to be. Interestingly, the computer was actually better than people at predicting when someone was too busy to be interrupted. The computer got it right 82 per cent of the time, humans 77 per cent. Fogarty speculates that this might be because people doing the interrupting are inevitably biased towards delivering their message, whereas computers don"t care. The first application for Hudson and Fogarty"s system is likely to be in an instant messaging system, followed by office phones and cellphones. "There is no technological roadblock (障碍) to it being deployed in a couple of years," says Hudson.

单选题About eight million school-age children are home alone after school. These are the hours when the number of violent crimes peaks and when youths are most likely to experiment with alcohol, tobacco, and drugs. Many older children take care of themselves after school for an hour or two until a parent comes home, and research suggests that some of these children are more at risk of poor grades and risky behaviors. Studies have been done to find out what helps to reduce these kinds of risky behaviors among youths. One study of Chicago neighborhoods showed that after-school programs resulted in less violence even in poor neighborhoods. After-school programs can help to reduce crime and violence because they offer activities to children and youths during their out-of-school time. In addition to helping youths make use of after-school hours, after-school programs provide teens with opportunities to develop caring relationships with adults. Studies have found that high-quality relationships with parents and other adults, as well as good use of time, are very important for healthy development in youth. After-school programs can also be used for teens who hang out at friends" houses and play basketball when a parent or other responsible adult is at home. The programs can also be helpful for formal after-school activities, including "drop-in" programs that are provided by organizations. Despite the benefits of after-school programs, there are many reasons why some parents do not use them. Programs may be too expensive, of poor quality, or hard to join. Some older children and young teens may refuse to attend programs that seem like they are just child care. Parents may feel uncertain about how much freedom is proper for children and youths who are beyond the traditional child care years. However, research supports the effectiveness of these programs in protecting middle school and high school youths from risk and harm.

单选题Sharks Perform a Service for Earth's Waters It is hard to get people to think of sharks as anything but a deadly enemy. They are thought to (51) people frequently. But these fish perform a (52) service for earth's waters and for human beings. Yet business and sport fishing are threatening their (53) . Some sharks are at risk of disappearing from (54) . Warm weather may influence both fish and shark activity. Many fish swim near coastal areas (55) their warm waters. Experts say sharks may follow the fish into the same areas, (56) people also swim. In fact, most sharks do not purposely charge at or bite humans. They are thought to mistake a person (57) a sea animal, such as a seal or sea lion. That is why people should not swim in the ocean when the sun goes down or comes up. Those are the (58) when sharks are looking for food. Experts also say that bright colors and shiny jewelry may cause sharks to attack. A shark has an extremely good sense of smell. It can find small amounts of substances in water, such as blood, body liquids and (59) produced by animals. These powerful (60) help sharks fred their food. Sharks eat fish, any (61) sharks, and plants that live in the ocean. Medical researchers want to learn more about the shark's body defense, and immune (62) against disease. Researchers know that sharks (63) quickly from injuries. They study the shark in hopes of finding a way to fight human disease. Sharks are important for the world's (64) . They eat injured and diseased fish. Their hunting activities mean that the numbers of other fish in ocean waters do not become too (65) . This protects the plants and other forms of life that exist in the oceans.

单选题These factors interact {{U}}intimately{{/U}} and cannot be separated. A. tensely B. nearly C. carefully D. closely

单选题A beautiful woman attended to me in that store yesterday.A. waited onB. talked toC. spoke toD. stayed with

单选题We were astonished to hear that their football team had won the champion.

单选题Cold air causes the arteries around the heart to {{U}}constrict{{/U}}.