大学英语四级300及答案解析.doc

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1、大学英语四级 300 及答案解析(总分：746.58，做题时间：130 分钟)一、Writing (30 minutes)(总题数：1，分数：30.00)1.For this part, you are allowed 30 minutes to write a composition about What Would Happen if There Were no Power in three paragraphs. You are given the first sentence or part of the first sentence of each paragraph. Your p

2、art of the composition should be no less than 120 words, not including the words given. 1. Ever since early last century, electricity has become an essential part of our modem life. 2. If there were no electric power, 3. Therefore, （分数：30.00）_二、Reading Comprehensio(总题数：1，分数：71.00)Wisdom Teeth Wisdom

3、 teeth are the last teeth to erupt. This occurs usually between the ages of 17 and 25. There remains a great deal of controversy regarding whether or not these teeth need to be removed. It is generally suggested that teeth that remain completely buried or un-erupted in a normal position are unlikely

4、 to cause harm. However, a tooth may become impacted due to lack of space and its eruption is therefore prevented by gum (齿龈), bone, another tooth or all three. If these impacted teeth are in an abnormal position, their potential for harm should be assessed. What are the Indications for Removing Wis

5、dom Teeth? Wisdom teeth generally cause problems when they erupt partially through the gum. The most common reasons for removing them are: Decay Saliva(唾液), bacteria and food particles can collect around an impacted wisdom tooth, causing it, or the next tooth to decay. It is very difficult to remove

6、 such decay. Pain and infection will usually follow. Gum Infection When a wisdom tooth is partially erupted, food and bacteria collect under the gum causing a local infection. This may result in bad breath, pain, and swelling. The infection can spread to involve the cheek and neck. Once the initial

7、episode occurs, each subsequent attack becomes more frequent and more severe. Pressure Pain Pain may also come from the pressure of the erupting wisdom tooth against other teeth. In some cases this pressure may cause the erosion of these teeth. When is the Best Time to Have Wisdom Teeth Removed? It

8、is now recommended by specialists that impacted wisdom teeth be removed between the ages of 14 and 22 years whether they are causing problems or not. Surgery is technically easier and patients recover much more quickly when they are younger. What is a relatively minor operation at 20 can become quit

9、e difficult in patients over 40. Also the risk of complications increases with age, and the healing process is slower. Should a Wisdom Tooth be Removed When an Acute Infection is Present? Generally, no. Surgery in the presence of infection can cause infection to spread and become more serious. First

10、ly, the infection must be controlled by local oral hygiene (卫生) and antibiotics (抗生素). The Pros and Cons of Wisdom Tooth Removal Some Pros of Removing a Wisdom Tooth: Wisdom teeth may be hard to access with your toothbrush. Over time, the accumulation of bacteria, sugars and acids may cause a cavity

11、 to form in the tooth. If it is not restored with a filling, the cavity(洞) may spread and destroy more tooth structure causing severe consequences to the tooth and surrounding supportive structures. Due to the difficulty of keeping these teeth clean with your daily home care, bacteria and food debri

12、s remaining on the wisdom teeth may present a foul smell causing bad breath. A wisdom tooth that is still under the gums in a horizontal position (rather than a vertical position) may exert pressure to the surrounding teeth, causing crowding and crooked teeth. This also may occur if there is not eno

13、ugh space in the mouth for the wisdom tooth. This may warrant braces to repair the damage. Some Cons of Removing the Wisdom Teeth: Depending on the size shape and position of the tooth, removal can vary from a simple extraction to a more complex extraction. With a simple extraction, there is usually

14、 little swelling and/or bleeding. More complex extraction will require special treatment which may result in more bruising, swelling and bleeding. However, your dental professional will provide you with post treatment instructions to minimize these side effects. Following an extraction, a condition

15、called “dry socket” may occur. If the blood clot (凝结) that formed in the extraction area becomes removed, it exposes the underlying bone. This condition is very painful, but resolves after a few days. It is preventable by following the post treatment instructions provided by your dental professional

16、. The longer you wait and the older you get, there is the potential for more problems to occur. This is because as you get older, the bone surrounding the tooth becomes more dense, making the tooth more difficult to remove. The healing process may also be slower. Post Operative Care: Do Not Disturb

17、the Wound In doing so you may invite irritation, infection and/or bleeding. Chew on the opposite side for the first 24 hours. Do Not Smoke for 12 Hours Smoking will promote bleeding and interfere with healing. Do Not Spit or Suck Through a Straw This will promote bleeding and may remove the blood cl

18、ot, which could result in a dry socket. Control of Bleeding If the area is not closed with stitches, a pressure pack made of folded sterile (消毒的) gauze (纱布) pads will be placed over the socket. It is important that this pack stay in place to control bleeding and to encourage clot formation. The gauz

19、e is usually kept in place for 30 minutes. If the bleeding has not stopped once the original pack is removed, place a new gauze pad over the extraction site. Control of Swelling After surgery, some swelling is to be expected. This can be controlled through the use of cold packs, which slow the circu

20、lation. A cold pack is usually placed at the site of swelling during the first 24 hours in a cycle of 20 minutes on and 20 minutes off. After the first 24 hours, it is advisable to rinse (漱口) with warm saltwater every two hours to promote healing, (one teaspoon of salt to eight ounces of warm water)

21、. Medication for Pain Control Pills such as Aspirin can be used to control minor discomfort following oral surgery. Stronger medicines may be prescribed by the dentist if the patient is in extreme discomfort. Diet and Nutrition A soft diet may be prescribed for the patient for a few days following s

22、urgery. Following the removal of your wisdom teeth it is important that you call your dentist if any unusual bleeding, swelling or pain occurs. The first 6-8 hours after the extraction are typically the worst, but are manageable with ice packs and non-prescription pain medication. You should also pl

23、an to see your dentist approximately one week later to ensure everything is healing well. It is very important to talk to your dentist about extraction procedure, risks, possible complications and outcomes of the removal of these teeth. The actual extraction may be done by a dentist or it may be ref

24、erred to an oral surgeon, who is a specialist. This decision is based on the dentists preference and the unique features of each individual case. If you are unsure about whether or not to proceed with the treatment suggested by your dental professional, it is a good idea to get a second opinion. If

25、you decide after consulting with a dentist not to have any teeth extracted, they should be monitored at every dental visit. （分数：71.00）(1).Dentists have reached an agreement that wisdom teeth should be removed in case it leads to other problems.（分数：7.10）A.YB.NC.NG(2).The best time to remove the impac

26、ted wisdom teeth is between the ages of 14 and 22 years because surgery is technically easier and patients recover much more quickly.（分数：7.10）A.YB.NC.NG(3).If there is an infection, the first thing to do is to stop it before get the wisdom tooth removed.（分数：7.10）A.YB.NC.NG(4).Wisdom tooth may become

27、 the cause of bad breath.（分数：7.10）A.YB.NC.NG(5).Removing the wisdom teeth involves very complex extraction.（分数：7.10）A.YB.NC.NG(6).After you get the wisdom teeth extracted youd better not spit or suck through a straw.（分数：7.10）A.YB.NC.NG(7).After your wisdom tooth is removed, you should rinse with war

28、m water every morning for two weeks.（分数：7.10）A.YB.NC.NG(8).If the position of the impacted teeth is abnormal, it is advisable to weigh_.（分数：7.10）_(9).Even if you have decided not to get your wisdom teeth removed, you still have to have them_.（分数：7.10）_(10).The painful time during the first 6-8 hours

29、 after the removal of the tooth can be controlled with_.（分数：7.10）_三、Listening Comprehens(总题数：1，分数：15.00)A.He prefers to stay at home.B.He enjoys listening to music at a bar.C.He would rather see a movie with his friends.D.He prefers restaurant to music bar.A.She sells tickets.B.She is going to a for

30、eign country.C.She has a drivers license.D.She has been accepted at a college.A.He must read a lot of books.B.He doesnt like history.C.He cant get the books he needs.D.He has lost his watch.A.The man shouldnt expect her to go along.B.She doesnt think she has enough money.C.Shell go even though the m

31、ovie is bad.D.The man should count the number of people going.A.Everything is slow in bad weather.B.Neither way is very fast.C.She has to take a train and bus to work.D.He should try both of them and compare.A.The man should learn to slow down.B.The man is always tired lately.C.They arent going very

32、 fast.D.They arent going to be on time.A.Its a very long one.B.It should take place as planned.C.The arrangements are uncertain so far.D.It was canceled on Friday.A.She prefers the stadium.B.She agrees with the man.C.The light isnt bright enough.D.The dining room isnt large enough.四、Section B(总题数：2，

33、分数：10.00)A.Because he didnt want to go to the womans party.B.Because he was deeply attracted by a program about Oprah Winfrey.C.Because he participated in Oprah Winfreys program.D.Because he forgot about the womans party.A.She is a US actress.B.She is a US speaker.C.She is the sponsor of a US talk s

34、how.D.She is the hostess of a US talk show.A.Oprah Winfrey has a distinguished family background.B.Oprah Winfrey is frank and genuine.C.Oprah Winfrey never spreads gossip or scandal.D.Oprah Winfrey was Americas first African-American news anchor.A.To ask for help finding a job.B.To find out what hes

35、 doing during the summer.C.To invite him to go shopping with her later.D.To ask him to give her some advice.A.Itd give her a chance to make a lot of money immediately.B.She could stay at a hotel at a discount.C.She might get a good job later.D.She might be able to get course credits for her work.A.S

36、hell have to work long hours.B.Shell have to work at the hotel during the school year.C.Her rent will be expensive.D.It doesnt pay very well.A.Make extra money while taking classes.B.Work in the clothing store.C.Take the job in the hotel.D.Continue her job search for a while.A.8,844.43meters.B.8,848

37、.43meters.C.8,840.43meters.D.8,844.03meters.A.The elevation of the datum plane is 0.7 meters shorter than that of 1975.B.Due to global warming, the snow and ice at the top has been melting.C.Mount Qomolangma is the worlds tallest peak on the earth.D.Surveying technologies have improved dramatically

38、in 20 years.A.Yes.B.No.C.Not mentioned.D.Hard to say.A.Some pessimistic experts.B.Environmentalists.C.Some optimistic experts.D.All of the above.A.It will become smaller.B.It will become safer.C.It will become more economical.D.It will become faster.A.The driver.B.The central computer.C.The car itse

39、lf.D.The authority.A.Given by the local government.B.Born by a large number of bitches.C.Bought from different cities and villages.D.Captured over grassland.A.11 -week course for control duty.B.11-week course for patrol duty.C.9-week course for control duty.D.9-week course for patrol duty.A.Catching

40、 runaway criminals.B.Scratching the hidden bombs.C.Patrolling the dangerous town.D.Drug-sniffing and bomb-sniffing.六、Section C(总题数：1，分数：10.00)“Humans should not try to avoid stress any more than they would shun food, love or (36) 1,“ said Dr. Hans Selye, the first physician to (37) 2the effects of s

41、tress on the body. While heres no question that continuous stress is (38) 3, several studies suggest that (39) 4situations in which youre able to rise to the occasion can be good for you. In a 2001 study of 158 hospital nurses, those who faced (40) 5work demands but coped with the challenge were mor

42、e likely to say they were in good (41) 6than those who felt they couldnt get the job done. Stress that you can manage may also (42) 7immune function. In a study at the Academic Center for Dentistry in Amsterdam, researchers put (43) 8through two stressful experiences. (44) 9. In the second, they wer

43、ent in control: They had to sit through a bloody video on surgical procedures. Those who did go on the memory test had an increase in levels of immunoglobulin A, an antibody thats the bodys first line of defense against germs. (45) 10 Stress prompts the body to produce certain stress hormones. (46)

44、11. But in the long run these hormones can have a effect on the body and brain. （分数：10.00）填空项 1:_填空项 1:_填空项 1:_填空项 1:_填空项 1:_填空项 1:_填空项 1:_填空项 1:_填空项 1:_填空项 1:_填空项 1:_七、Reading Comprehensio(总题数：2，分数：355.00)New ice core samples taken from the centre of the Greenland ice-sheet have given a detailed re

45、cord of the last “interglacial (间冰期)“ which rail from about 135,000 to 115,000 years ago. The cores, taken from a depth of 2,780 to 2,870 metres, show that during this period the climate oscillated(摆动) between three states instead of remaining in one, as in the whole of recorded human history. The m

46、iddle state was like our own, but the others were either much colder or warmer. Worse, it seems that the climate flipped from one condition to another very rapidly. “It apparently took very little time, perhaps less than a decade or two, to shift between the states,“ Dr. J.C. W. White of the Institu

47、te of Arctic and Alpine Research at the University of Colorado wrote earlier this year in the scientific journal, Nature: “We humans have built a remarkable socio-economic system during perhaps the only time when it could be built, when the climate was stable enough to let us develop the agricultural infrastructure(基础设施) required to maintain an advanced society.“ We do not know why we have been so blessed. But if the Earth had an operating manual, the chapter on climate might begin with a warning that the system has been adjusted at the factory for o