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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.
在本节中，你将听到15个对话，每个对话有一个问题。请从[A]、[B]、[C]三个选项中选出答案。每段话后有15秒钟的停顿，以便回答问题和阅读下一问题。每段对话读两遍。 下面，请听这些对话。 Who are the man and the woman
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.
The Best Way to Reduce Your Weight You hear this: "No wonder you are fat. All you ever do is eating." You feel sad: "I skip my breakfast and supper. I run every morning and evening. What else can I do" Basically you can do nothing. Your genes, not your life habits, determine your weight and your body constantly tries to maintain it. Albert Stunkard of the University of Pennsylvania found from experiments that, "80 percent of the children of two obese parents become obese, as compared with no more than 14 percent of the offspring of two parents of normal weight." How can obese people become normal or even thin through dieting Well, dieting can be effective, but the health costs are tremendous. Jules Hirsch, a research physician at Rockefeller University, did a study of eight fat people. They were given a liquid formula providing 600 calories a day. After more than 10 weeks, the subjects lost 45kg on average. But after leaving the hospital, they all regained. The results were surprising by metabolic measurement, fat people who lost large amounts of weight seemed like they were starving. They had psychiatric problems. They dreamed of food or breaking their diet. They were anxious and depressed; some were suicidal. They hid food in their rooms. Researchers warn that it is possible that weight reduction doesn’t result in normal weight, but in an abnormal state resembling that of starved non-obese people. Thin people, however, suffer from the opposite: They have to make a great effort to gain weight. Ethan Sims, of the University of Vermont, got prisoners to volunteer to gain weight. In four to six months, they ate as much as they could. They succeeded in increasing their weight by 20 to 25 percent. But months after the study ended, they were back to normal weight and stayed there. This did not mean that people are completely without hope in controlling their weight. It means that those who tend to be fat will have to constantly battle their genetic inheritance if they want to significantly lower their weight. The findings also provide evidence for something scientists thought was true--each person has a comfortable weight range. The range might be as much as 9kg. Someone might weigh 60-69kg without too much effort. But going above or below the natural weight range is difficult. The body resists by feeling hungry or full and changing the metabolism to push the weight back to the range it seeks. What happened to the eight fat people after they left the hospital
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