大学四级-14及答案解析.doc

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1、大学四级-14 及答案解析(总分：712.00，做题时间：90 分钟)一、BPart Writing(总题数：1，分数：106.00)1.锻炼身体和平衡饮食 2哪个是保持健康的最佳办法 3我的观点（分数：106.00）_二、BPart Reading (总题数：1，分数：70.00)BDirections:/BI In this part, you will have 15 minutes to go over the passage quickly and answer the questions on Answer Sheet 1. For questions 1-7, choose th

2、e best answer from the four choices marked A, B, C and D. For questions 8-10, complete the sentences with the information given in the passage./IB How Exercises Work/BWhen you exercise or compete in sports, you notice several things about your body. You breathe heavier and faster, your heart beats f

3、aster, your muscles hurt and you sweat. These are all normal responses to exercise whether you work out regularly or only once in a while or whether you are a “weekend warrior“ or a trained athlete. When you watch world-class athletes compete, you see the same responses, only magnified.The body bas

4、an incredibly complex set of processes to meet the demands of working muscles. Every system in the body is involved. In this article, we will look at how your body responds to strenuous exercise-how muscles, blood circulation, breathing and body heat are affected. You will also see how these respons

5、es can be enhanced by training.BYour Bodys Response to Exercise/BAny type of exercise uses your muscles. Running, swimming, weightlifting-any sport you can imagine-uses different muscle groups to generate motion. In running and swimming, your muscles are working to accelerate your body and keep it m

6、oving. In weightlifting, your muscles are working to move a weight. Exercise means muscle activity!As you use your muscles, they begin to make demands on the rest of the body. In strenuous exercise, just about every system in your body either focuses its efforts on helping the muscles do their work,

7、 or it shuts down. For example, your heart beats faster during strenuous exercise so that it can pump more blood to the muscles, and your stomach shuts down during strenuous exercise so that it does not waste energy that the muscles can use.When you exercise, your muscles act something like electric

8、 motors. Your muscles take in a source of energy and they use it to generate force. An electric motor uses electricity to supply its energy. Your muscles are biochemical motors, and they use a chemical called adenosine triphosphate (ATP) for their energy source. During the process of “burning“ ATP,

9、your muscles need three things:They need oxygen, because chemical reactions require ATP and oxygen is consumed to produce ATP.They need to eliminate metabolic wastes (carbon dioxide, lactic acid) that the chemical reactions generate.They need to get rid of heat. Just like an electric motor, a workin

10、g muscle generates heat that it needs to get rid of.In order to continue exercising, your muscles must continuously make ATP. To make this happen, your body must supply oxygen to the muscles and eliminate the waste products and heat. The more strenuous the exercise, the greater the demands of workin

11、g muscle. If these needs are not met, then exercise will cease-that is, you become exhausted and you wont be able to keep going.To meet the needs of working muscle, the body has an orchestrated response involving the heart, blood vessels, nervous system, lungs, liver and skin. It really is an amazin

12、g system!BExercise and ATP/BFor your muscles-in fact, for every cell in your body-the source Of energy that keeps everything going is called ATP. Adenosine triphosphate (ATP) is the biochemical way to store and use energy.The entire reaction that turns ATP into energy is a bit complicated, but here

13、is a good summary:Chemically, ATP is an adenine nucleotide bound to three phosphates.There is a lot of energy stored in the bond between the second and third phosphate groups that can be used to fuel chemical reactions.When a cell needs energy, it breaks this bond to form adenosine diphosphate ( ADP

14、 ) and a free phosphate molecule.In some instances, the second phosphate group can also be broken to form adenosine monophosphate (AMP).When the cell has excess energy, it stores this energy by forming ATP from ADP and phosphate.ATP is required for the biochemical reactions involved in any muscle co

15、ntraction. As the work of the muscle increases, more and more ATP gets consumed and must be replaced in order for the muscle to keep moving.Because ATP is so important, the body has several different systems to create ATP. These systems work together in phases. The interesting thing is that differen

16、t forms of exercise use different systems, so a sprinter is getting ATP in a completely different way from a marathon runner!ATP comes from three different biochemical systems in the muscle, in this order: phosphagen system glycogen-lactic acid system aerobic respirationBExercise and the Phosphagen

17、System/BA muscle cell has some amount of ATP floating around that it can use immediately, but not very much-only enough to last for about three seconds. To replenish the ATP levels quickly, muscle cells contain a high-energy phosphate compound called creatine phosphate. The phosphate group is remove

18、d from creatine phosphate by an enzyme called creatine kinase, and is transferred to ADP to form ATP. The cell turns ATP into ADP, and the phosphagen rapidly turns the ADP back into ATP. As the muscle continues to work, the creatine phosphate levels begin to decrease. Together, the ATP levels and cr

19、eatine phosphate levels are called the phosphagen system. Tile phosphagen system can supply the energy needs of working muscle at a high rate, but only for 8 to l0 seconds.BExercise and the Glycogen-Lactic Acid System/BMuscles also have big reserves of a complex carbohydrate called glycogen. Glycoge

20、n is a chain of glucose molecules. A cell splits glycogen into glucose. Then the cell uses anaerobic metabolism (anaerobic means “without oxygen“) to make ATP and a byproduct called lactic acid from the glucose.About 12 chemical reactions take place to make ATP under this process, so it supplies ATP

21、 at a slower rate than the phosphagen system. The system can still act rapidly and produce enough ATP to last about 90 seconds. This system does not need oxygen, which is handy because it takes the heart and lungs some time to get their act together. It is also handy because the rapidly contracting

22、muscle squeezes off its own blood vessels, depriving itself of oxygen-rich blood.There is a definite limit to anerobic respiration because of the lactic acid. The acid is what makes your muscles hurt. Lactic acid builds up in the muscle tissue and causes the fatigue and soreness you feel in your exe

23、rcising muscles.BExercise and Aerobic Respiration/BBy two minutes of exercise, the body responds to supply working muscles with oxygen. When oxygen is present, glucose can be completely broken down into carbon dioxide and water in a process called aerobic respiration. The glucose can come from three

24、 different places:remaining glycogen supplies in the muscles;breakdown of the livers glycogen into glucose, which gets to working muscle through the bloodstream;absorption of glucose from food in the intestine, which gets to working muscle through the bloodstream.Aerobic respiration can also use fat

25、ty acids from fat reserves in muscle and the body to produce ATP. In extreme cases (like starvation). proteins can also be broken down into amino acids and used to make ATP. Aerobic respiration would use carbohydrates first, then fats and finally proteins, if necessary. Aerobic respiration takes eve

26、n more chemical reactions to produce ATP than either of the above systems. Aerobic respiration produces ATP at the slowest rate of the three systems, but it can continue to supply ATP for several hours or longer, so long as the fuel supply lasts.BWhat Happens When You Exercise/BSo imagine that you s

27、tart running. Heres what happens:The muscle cells bum off the ATP they have floating around in about 3 seconds.The phosphagen system kicks in and supplies energy for 8 to 10 seconds. This would be the major energy system used by the muscles of a 100-meter sprinter or weight lifter, where rapid accel

28、eration, short-duration exercise occurs.If exercise continues longer, then the glycogen-lactic acid system kicks in. This would be true for short-distance exercises such as a 200- or 400-meter dash or 100-meter swim.Finally, if exercise continues, then aerobic respiration takes over. This would occu

29、r in endurance events such as an 800- meter dash, marathon run, rowing, cross-country skiing and distance skating.When you start to look closely at how the human body works, it is truly an amazing machine!（分数：70.00）(1).Your muscles are working to move a weight when you are _. A. swimming C. running

30、B. weightlifting D. high jumping（分数：7.00）A.B.C.D.(2).During the process of “burning“ ATP, your muscles need _. A. to eliminate heat C. carbon dioxide B. lactic acid D. to add energy（分数：7.00）A.B.C.D.(3).When the cell has excess energy, it stores this energy by forming _. A. phosphate C. ADP B. AMP D.

31、 ATP（分数：7.00）A.B.C.D.(4).The body has several different systems to create _, because it is very important. A. AMP C. ATP B. ADP D. phosphate molecule（分数：7.00）A.B.C.D.(5).Muscle cells contain a high-energy phosphate compound called _. A. creatine kinase C. phosphate group B. creatine phosphate D. enz

32、yme（分数：7.00）A.B.C.D.(6).What makes your muscles hurt? A. Glucose. C. Oxygen-rich blood. B. ATP. D. Lactic acid.（分数：7.00）A.B.C.D.(7).Glucose can be completely broken down into carbon dioxide and water when oxygen is present in the process called _. A. anaerobic metabolism C. aerobic respiration B. “b

33、urning“ ATP D. phosphagen system（分数：7.00）A.B.C.D.(8).When you are starving, proteins can also be broken down into（分数：7.00）填空项 1:_(9).When you start running, the muscle cells burn off the ATP they have floating around in（分数：7.00）填空项 1:_(10).Aerobic respiration would occur in（分数：7.00）填空项 1:_三、BPart Li

34、stenin(总题数：0，分数：0.00)四、BSection A/B(总题数：3，分数：105.00)BDirections:/BI In this section, you will hear 8 short conversations and 2 long conversations. At the end of each conversation, one or more questions will be asked about what was said. Both the conversation and the questions will be spoken only onc

35、e. After each question there will be a pause. During the pause, you must read the four choices marked A, B, C and D, and decide which is the best answer. Then mark the corresponding letter on Answer Sheet 2 with a single line through the centre./IBQuestions 11 to 18 are based on the conversation you

36、 have just heard./B （分数：56.00）(1). A. A holiday. C. Work. B. Luck. D. An accident.（分数：7.00）A.B.C.D.(2). A. She prefers the stadium. C. The light isnt bright enough. B. She agrees with the man. D. The dining hall isnt large enough.（分数：7.00）A.B.C.D.(3). A. Two hours by train. C. One hour by bus. B. On

37、e hour by train. D. One hour by car.（分数：7.00）A.B.C.D.(4). A. English. C. Australian. B. Canadian. D. Austrian.（分数：7.00）A.B.C.D.(5). A. Straight ahead on the street. C. On the left. B. On the right. D. Over there.（分数：7.00）A.B.C.D.(6). A. Crowns. C. Peters. B. Mrs. Petersons. D. Mr. Petersons.（分数：7.00

38、）A.B.C.D.(7). A. Dentist and patient. C. Roommates. B. Schoolmates. D. Workmates.（分数：7.00）A.B.C.D.(8). A. Because she was not at home. C. Because she was washing her hair. B. Because she didnt hear the telephone ting. D. Because she didnt want to answer.（分数：7.00）A.B.C.D.BQuestions 19 to 22 are based

39、 on the conversation you have just heard./B （分数：28.00）(1). A. She generally doesnt allow people to borrow it. C. She bought it from a friend. B. She is trying to sell it. D. It has broken down before.（分数：7.00）A.B.C.D.(2). A. The woman could probably repay it herself. C. It probably wont cost a lot t

40、o repair. B. Its rather small. D. Its probably difficult to drive.（分数：7.00）A.B.C.D.(3). A. He only works on new cars. C. He is one of her neighbors. B. He has fixed her car before. D. He will probably overcharge her.（分数：7.00）A.B.C.D.(4). A. Take the woman to her home. C. Help the woman pay the mecha

41、nics bill. B. Test-drive the womans car. D. Help the woman fix her car.（分数：7.00）A.B.C.D.BQuestions 23 to 25 are based on the conversation you have just heard./B （分数：21.00）(1). A. The possible existence of life on other planets. C. A technical problem that astronomers cant solve. B. Methods for build

42、ing powerful new telescopes. D. The discovery of planets orbiting distant stars.（分数：7.00）A.B.C.D.(2). A. They studied variations in the appearance Of the parent stars. B. They were able to see the planets with a telescope. C. They compared the parent stars to the Sun. D. They sent astronauts on a mi

43、ssion into space.（分数：7.00）A.B.C.D.(3). A. Their surface features. C. Their temperature. B. Their chemical composition. D. Their age.（分数：7.00）A.B.C.D.五、BSection B/B(总题数：3，分数：70.00)BDirections:/BI In this section, you will hear 3 short passages. At the end of each passage, you will hear some questions

44、. Both the passage and the questions will be spoken only once. After you hear a question, you must choose the best answer from the four choices marked A, B, C and D. Then mark the corresponding letter on Answer Sheet 2 with a single line through the center./IBPassage One Questions 26 to 28 are based

45、 on the passage you have just heard. /B （分数：21.00）(1). A. She does her shopping. C. She eats a lot of things. B. She drinks extra tea. D. She sleeps a great deal.（分数：7.00）A.B.C.D.(2). A. Problems with the teachers. C. Problems with class work B. Problems with family members or friends. D. Problems w

46、ith a part-time job.（分数：7.00）A.B.C.D.(3). A. Talking to someone over the phone. C. Playing a video game. B. Drinking some diet coke. D. Drinking extra tea.（分数：7.00）A.B.C.D.BPassage Two Questions 29 to 31 are based on the passage you have just heard. /B （分数：21.00）(1). A. They were able to fly it in t

47、he air. B. They were able to stay up in the air for half an hour and more in the machine. C. They were able to carry travelers. D. They were able to fly in around Dayton.（分数：7.00）A.B.C.D.(2). A. Nothing. C. Hardly anything. B. A lot. D. A little.（分数：7.00）A.B.C.D.(3). A. The reporters didnt believe what people told them about the flights. B. The Government didnt give the Wrights any money. C. The Government thought the Wrights wanted money in order to build an airplane. D. At the time it seemed no one could understand them.（分数：7.00）A.B.C.D.BPassage ThreeQuestions 32 to 35 are based