Learning Disabilities Learning disabilities are very common. They affect perhaps 10 percent of all children. Four times as many boys as girls have learning disabilities. Since about 1970, new research has helped brain scientists understand these problems better. Scientists now know there are many different kinds of learning disabilities and that they are caused by many different things. There is no longer any question that all learning disabilities result from differences in the way the brain is organized. You cannot look at a child and tell if he or she has a learning disability. There is no outward sign of the disorder. So some researchers began looking at the brain itself to learn what might be wrong. In one study, researchers examined the brain of a learning-disabled person who had died in an accident. They found two unusual things. One involved cells in the left side of the brain, which control language. These cells normally are white. In the learning disabled person, however, these cells were gray. The researchers also found that many of the nerve cells were not in a line the way they should have been. The nerve cells were mixed together. The study was carried out under the guidance of Norman Geschwind, an early expert on learning disabilities. Doctor Geschwind proposed that learning disabilities resulted mainly from problems in the left side of the brain. He believed this side of the brain failed to develop normally. Probably, he said, nerve cells there did not connect as they should. So the brain was like an electrical device in which the wires were crossed. Other researchers did not examine brain tissue. Instead, they measured the brain’ s electrical activity and made a map of the electrical signals. Frank Dully experimented with this technique at Children’ s Hospital Medical Center in Boston. Doctor Dully found large differences in the brain activity of normal children and those with reading problems. The differences appeared throughout the brain. Doctor Dully said his research is evidence that disabilities involve damage to a wide area of the brain, not just the left side.

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A. when it is absorbed by matter B. when it is cloudy C. because they can pass through solid objects D. when the sunrays are fierce E. when a change in the nucleus of an atom takes place F. when electron rearrangement takes place

Media and Current Events The media can impact current events. As a graduate student at Berkeley in the 1960s, I remember experiencing the events related to the People’ s Park that were occurring on campus. Some of these events were given national media coverage in the press and on TV. I found it interesting to compare my impressions of what was going on with perceptions obtained from the news media. I could begin to see events of that time feed on news coverage. This also provided me with some healthy insights into the distinctions between these realities. Electronic media are having a greater impact on the people’ s lives every day. People gather more and more of their impressions from representations. Television and telephone communications are linking people to a global village, or what one writer calls the electronic city. Consider the information that television brings into your home every day. Consider also the contact you have with others simply by using telephone. These media extend your consciousness and your contact. For example, the video coverage of the 1989 San Francisco earthquake focused on “live action“ such as the fires or the rescue efforts. This gave the viewer the impression of total disaster. Television coverage of the Iraqi War also developed an immediacy. CNN reported events as they happened. This coverage was distributed worldwide. Although most people were far away from these events, they developed some perception of these realities. In 1992, many people watched in horror as riots broke out on a sad Wednesday evening in Los Angeles, seemingly fed by video coverage from helicopters. This event was triggered by the verdict(裁定)in the Rodney King beating. We are now in an age where the public can have access to information that enables it to make its own judgments, and most people, who had seen the video of this beating, could not understand how the jury(陪审团)was able to acquit(宣布无罪)the policemen involved. Media coverage of events as they occur also provides powerful feedback that influences events. This can have harmful results, as it seemed on that Wednesday night in Los Angeles. By Friday night the public got to see Rodney King on television pleading, “Can we all get along?“ By Saturday, television seemed to provide positive feedback as the Los Angeles riot turned out into a rally for peace. The television showed thousands of people marching with banners and cleaning tools. Because of that, many more people turned out to join the peaceful event they saw unfolding(展开)on television. The real healing, of course, will take much longer, but electronic media will continue to be a part of that process.

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Learning Disabilities Learning disabilities are very common. They affect perhaps 10 percent of all children. Four times as many boys as girls have learning disabilities. Since about 1970, new research has helped brain scientists understand these problems better. Scientists now know there are many different kinds of learning disabilities and that they are caused by many different things. There is no longer any question that all learning disabilities result from differences in the way the brain is organized. You cannot look at a child and tell if he or she has a learning disability. There is no outward sign of the disorder. So some researchers began looking at the brain itself to learn what might be wrong. In one study, researchers examined the brain of a learning-disabled person who had died in an accident. They found two unusual things. One involved cells in the left side of the brain, which control language. These cells normally are white. In the learning disabled person, however, these cells were gray. The researchers also found that many of the nerve cells were not in a line the way they should have been. The nerve cells were mixed together. The study was carried out under the guidance of Norman Geschwind, an early expert on learning disabilities. Doctor Geschwind proposed that learning disabilities resulted mainly from problems in the left side of the brain. He believed this side of the brain failed to develop normally. Probably, he said, nerve cells there did not connect as they should. So the brain was like an electrical device in which the wires were crossed. Other researchers did not examine brain tissue. Instead, they measured the brain’ s electrical activity and made a map of the electrical signals. Frank Dully experimented with this technique at Children’ s Hospital Medical Center in Boston. Doctor Dully found large differences in the brain activity of normal children and those with reading problems. The differences appeared throughout the brain. Doctor Dully said his research is evidence that disabilities involve damage to a wide area of the brain, not just the left side.

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Look After Your Voice Often speakers at a meeting experience dry mouths and ask for a glass of water. You can solve the problem by activating the saliva(唾液)in your mouth. First gently bite the edges of your tongue with your teeth. Or, press your entire tongue to the bottom of your mouth and hold it there until the saliva flow. Or you can imagine that you are slicing(切片)a big juicy lemon and sucking(吮吸)the juice. Before you begin your talk, be kind to your voice. Avoid milk or creamy drinks which coat your throat. Keep your throat wet by drinking a little sweetened warm tea or diluted(稀释的)fruit juice. If you sense that you are losing your voice, stop talking completely. Save your voice for your speech. You may feel foolish using paper to write notes, but the best thing you can do is to rest your voice. If you need to see a doctor, perhaps you can get some advice from a professional singer. In the meantime, do not even talk in a low voice. What about drinking alcohol to wet your throat? I advice you not to touch alcohol before speaking. The problem with alcohol is that one drink gives you a little confidence. The second drink gives you even more confidence. Finally you will feel all-powerful and you will feel you can do everything, but in fact your brain and your mouth do not work together properly. Save the alcohol until you finish speaking. Perhaps you want to accept the advice, but you may wonder if you can ever change the habits of a lifetime. Of course you can. Goethe, who lived before indoor skating sinks or swimming pools, said, “We learn to skate in the summer and swim in the winter. “ Take this message to heart and give yourself time to develop your new habits. If you are willing to change, you will soon be able to say that you will never forget these techniques because they became a part of your body.

Electromagnetic Energy 1 White light seems to be a combination of all colors. The energy that comes from a source of light is not limited to the kind of energy you can see. Heat is given off by a flame or an electric light. On a cloudy day it is possible to get a sunburn even though you feel cool. Visible light and the kinds of energy that produce warmth and sunburn are examples of electromagnetic energy. 2 The sun is 93 million miles from the earth. Yet we can use energy from the sun because electromagnetic energy travels through space. 3 Many other kinds of energy are also types of electromagnetic energy. Radio, television, and radar signals travel from transmitters to receivers as low-energy electromagnetic waves. Infrared(红外线的)radiation is an electromagnetic wave. When it is absorbed by matter, heat is produced. Waves of infrared and visible light have more energy than waves of radio, television, or radar. Ultraviolet rays(紫外线)and X-rays are electromagnetic waves with even greater amounts of energy. Infrared radiation is used in cooking food and heating buildings. Sunlight and electric lights are part of our requirements for normal living. Ultraviolet radiation is useful in killing certain disease organisms. X-rays and gamma rays have so much energy that they travel through solid objects. They can be used to detect and treat cancer. X-rays are used in industry to find hidden cracks in metal, and in medicine to reveal broken bones. 4 Usually we use electricity to generate electromagnetic energy. The source of most of our energy is the sun. Heat from the sun causes water to evaporate. When the water falls to the earth as rain, some of it is trapped behind dams and then used to operate electric generators. Other generators are powered by coal, but the energy stored in coal came from the sun, too. 5 Until recently, the source of the tremendous amount of energy given off by the sun was a puzzle. If the sun depended on chemical reactions, it would have used up all its energy long ago. Experiments with electromagnetic radiation led to the theory that mass can be converted into energy. About forty years after the theory was proposed, nuclear energy was harnessed(利用)by man. Chemical energy comes from electron(电子)rearrangement. Nuclear energy comes from a change in the nucleus of an atom. Compared with chemical reactions, nuclear reactions release millions of times more energy per pound of fuel. We now believe that the sun’ s energy comes from the nuclear reactions in which hydrogen is changed into helium(氦). 6 Nuclear energy is beginning to compete with coal as an economical source of power to generate electricity. It is also being used to operate engines in large ships. Scientists continue to seek new and better methods of obtaining and using energy. A. Nuclear Reactions as the Uasting Source of the Sun s Energy B. The Most Important Source of Energy C. Types of Electromagnetic Energy D. The Machines Used for Energy Generation E. Seeking New Sources of Energy F. The Use of Ultraviolet Radiation in Medicine

Which of the following is NOT mentioned in the passage?

Scientists found that the brain cells of a learning-disabled person differ from those of a normal person in______.

All of the following statements are true EXCEPT that______.

Doctor Dully believed that______.

According to the passage we can conclude that further researches should be made______.