2002年6月全国大学英语四级考试真题和答案
Part I Listening Comprehension (20 minutes)
Section A
Directions,In this section,you will hear 10 short conversations,At the end of each conversation,a question will be asked about what was said,Both the conversation and the question will be spoken only once,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 the Answer Sheet with a single line through the center.
Example:
You will hear:
You will read:
A) At the office.
B) In the waiting room.
C) At the airport.
D) In a restaurant.
From the conversation we know that the two were talking about some work they had to finish in the evening,This is most likely to have taken place at the office,Therefore,A),At the office” is the best answer,You should choose [A] on the Answer Sheet and mark it with a single line through the center.
Sample Answer [A] [C] [D]
1,A) His father.
B) His mother.
C) His brother.
D) His sister.
2,A) A job opportunity.
B) A position as general manager.
C) A big travel agency.
D) An inexperienced salesman.
3,A) Having a break.
B) Continuing the meeting.
C) Moving on to the next item.
D) Waiting a little longer.
4,A) The weather forecast says it will be fine.
B) The weather doesn’t count in their plan.
C) They will not do as planned in case of rain.
D) They will postpone their program if it rains.
5,A) He wishes to have more courses like it.
B) He finds it hard to follow the teacher.
C) He wishes the teacher would talk more.
D) He doesn’t like the teacher’s accent.
6,A) Go on with the game.
B) Draw pictures on the computer.
C) Review his lessons.
D) Have a good rest.
7,A) She does not agree with Jack.
B) Jack’s performance is disappointing.
C) Most people will find basketball boring.
D) She shares Jack’s opinion.
8,A) The man went to a wrong check-in counter.
B) The man has just missed his flight.
C) The plane will leave at 9:14.
D) The plane’s departure time remains unknown.
9,A) At a newsstand.
B) At a car dealer’s.
C) At a publishing house.
D) At a newspaper office.
10,A) He wants to get a new position.
B) He is asking the woman for help.
C) He has left the woman a good impression.
D) He enjoys letter writing.
Section B
Directions,In this section,you will hear 3 short passages,At the end of each passage,you will hear some questions,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 the Answer Sheet with a single line through the center.
Passage one
Questions 11 to 13 are based on the passage you have just heard.
11,A) They are interested in other kinds of reading.
B) They are active in voluntary services.
C) They tend to be low in education and in income.
D) They live in isolated areas.
12,A) The reasons why –people don’t read newspapers are more complicated than assumed.
B) There are more uneducated people among the wealthy than originally expected.
C) The number of newspaper readers is steadily increasing.
D) There are more nonreaders among young people nowadays.
13,A) Lowering the prices of their newspapers.
B) Shortening their news stories.
C) Adding variety to their newspaper content.
D) Including more advertisements in their newspapers.
Passage Two
Questions 14 to 17 are based on the passage you have just heard.
14,A) A basket.
B) A cup.
C) A egg.
D) An oven.
15,A) To let in the sunshine.
B) To serve as its door.
C) To keep the nest cool.
D) For the bird to lay eggs.
16,A) Branches.
B) Grasses.
C) Mud.
D) Straw.
17,A) Some are built underground.
B) Some can be eaten.
C) Most are sewed with grasses.
D) Most are dried by the sun.
Passage Three
Questions 18 to 20 are based on the passage you have just heard.
18,A) To examine the chemical elements in the Ice Age.
B) To look into the pattern of solar wind activity.
C) To analyze the composition of different trees.
D) To find out the origin of carbon-14 on Earth.
19,A) The lifecycle of trees.
B) The number of trees.
C) The intensity of solar burning.
D) The quality of air.
20,A) It affects the growth of trees.
B) It has been increasing since the Ice Age.
C) It is determined by the chemicals in the air.
D) It follows a certain cycle.
Part II Reading Comprehension (35 minutes)
Directions,There are 4 passages in this part,Each passage is followed by some questions or unfinished statements,For each of them there are four choices marked A),B),C) and D),You should decide on the best choice and mark the corresponding letter on the Answer Sheet with a single line through the center.
Passage One
Questions 21 to 25 are based on the following passage.
In the 1960s,medical researchers Thomas Holmes and Richard Rahe developed a checklist of stressful events,They appreciated the tricky point that any major change can be stressful,Negative events like,serious illness of a family member” were high on the list,but so were some positive life-changing events,like marriage,When you take the Holmes-Rahe test you must remember that the score does not reflect how you deal with stress—it only shows how much you have to deal with,And we now know that the way you handle these events dramatically affects your chances of staying healthy.
By the early 1970s,hundreds of similar studies had followed Holmes and Rahe,And millions of Americans who work and live under stress worried over the reports,Somehow,the research got boiled down to a memorable message,Women’s magazines ran headlines like,Stress causes illness!” If you want to stay physically and mentally healthy,the articles said,avoid stressful events.
But such simplistic advice is impossible to follow,Even if stressful events are dangerous,many—like the death of a loved one—are impossible to avoid,Moreover,any warning to avoid all stressful events is a prescription (处方) for staying away from opportunities as well as trouble,Since any change can be stressful,a person who wanted to be completely free of stress would never marry,have a child,take a new job or move.
The notion that all stress makes you sick also ignores a lot of what we know about people,It assumes we’re all vulnerable (脆弱的) and passive in the face of adversity (逆境),But what about human initiative and creativity? Many come through periods of stress with more physical and mental vigor than they had before,We also know that a long time without change or challenge can lead to boredom,and physical and metal strain.
21,The result of Holmes-Rahe’s medical research tells us ________.
A) the way you handle major events may cause stress
B) what should be done to avoid stress
C) what kind of event would cause stress
D) how to cope with sudden changes in life
22,The studies on stress in the early 1970’s led to ________.
A) widespread concern over its harmful effects
B) great panic over the mental disorder it could cause
C) an intensive research into stress-related illnesses
D) popular avoidance of stressful jobs
23,The score of the Holmes-Rahe test shows ________.
A) how much pressure you are under
B) how positive events can change your life
C) how stressful a major event can be
D) how you can deal with life-changing events
24,Why is,such simplistic advice” (Line 1,Para,3) impossible to follow?
A) No one can stay on the same job for long.
B) No prescription is effective in relieving stress.
C) People have to get married someday.
D) You could be missing opportunities as well.
25,According to the passage people who have experienced ups and downs may become ________.
A) nervous when faced with difficulties
B) physically and mentally strained
C) more capable of coping with adversity
D) indifferent toward what happens to them
Passage Two
Questions 26 to 30 are based on the following passage.
Most episodes of absent-mindedness—forgetting where you left something or wondering why you just entered a room—are caused by a simple lack of attention,says Schacter.,You’re supposed to remember something,but you haven’t encoded it deeply.”
Encoding,Schacter explains,is a special way of paying attention to an event that has a major impact on recalling it later,Failure to encode properly can create annoying situations,If you put your mobile phone in a pocket,for example,and don’t pay attention to what you did because you’re involved in a conversation,you’ll probably forget that the phone is in the jacket now hanging in you wardrobe (衣柜).,Your memory itself isn’t failing you,” says Schacter.,Rather,you didn’t give your memory system the information it needed.”
Lack of interest can also lead to absent-mindedness.,A man who can recite sports statistics from 30 years ago,” says Zelinski,“may not remember to drop a letter in the mailbox.” Women have slightly better memories than men,possibly because they pay more attention to their environment,and memory relies on just that.
Visual cues can help prevent absent-mindedness,says Schacter.,But be sure the cue is clear and available,” he cautions,If you want to remember to take a medication (药物) with lunch,put the pill bottle on the kitchen table—don’t leave it in the medicine chest and write yourself a note that you keep in a pocket.
Another common episode of absent-mindedness,walking into a room and wondering why you’re there,Most likely,you were thinking about something else.,Everyone does this from time to time,” says Zelinski,The best thing to do is to return to where you were before entering the room,and you’ll likely remember.
26,Why does the author think that encoding properly is very important?
A) It helps us understand our memory system better.
B) It enables us to recall something form our memory.
C) It expands our memory capacity considerably.
D) It slows down the process of losing our memory.
27,One possible reason why women have better memories than men is that ________.
A) they have a wider range of interests
B) they are more reliant on the environment
C) they have an unusual power of focusing their attention
D) they are more interested in what’s happening around them
28,A note in the pocket can hardly serve as a reminder because ________.
A) it will easily get lost
B) it’s not clear enough for you to read
C) it’s out of your sight
D) it might get mixed up with other things
29,What do we learn from the last paragraph?
A) If we focus our attention on one thing,we might forget another.
B) Memory depends to a certain extent on the environment.
C) Repetition helps improve our memory.
D) If we keep forgetting things,we’d better return to where we were.
30,What is the passage mainly about?
A) The process of gradual memory loss.
B) The causes of absent-mindedness.
C) The impact of the environment on memory.
D) A way if encoding and recalling.
Passage Three
Questions 31 to 35 are based on the following passage.
It is hard to track the blue whale,the ocean’s largest creature,which has almost been killed off by commercial whaling and is now listed as an endangered species,Attaching radio devices to it is difficult,and visual sightings are too unreliable to give real insight into its behavior.
So biologists were delighted early this year when,with the help of the Navy,they were able to track a particular blue whale for 43 days,monitoring its sounds,This was possible because of the Navy’s formerly top-secret system of underwater listening devices spanning the oceans.
Tracking whales is but one example of an exciting new world just opening to civilian scientists after the cold war as the Navy starts to share and partly uncover its global network of underwater listening system built over the decades to track the ships of potential enemies.
Earth scientists announced at a news conference recently that they had used the system for closely monitoring a deep-sea volcanic eruption (爆发) for the first time and that they plan similar studies.
Other scientists have proposed to use the network for tracking ocean currents and measuring changes in ocean and global temperatures.
The speed of sound in water is roughly one mile a second—slower than through land but faster than through air,What is most important,different layers of ocean water can act as channels for sounds,focusing them in the same way a stethoscope (听诊器) does when it carries faint noises from a patient’s chest to a doctor’s ear,This focusing is the main reason that even relatively weak sounds in the ocean,especially low-frequency ones,can often travel thousands of miles.
31,The passage is chiefly about ________.
A) an effort to protect an endangered marine species
B) the civilian use of a military detection system
C) the exposure of a U.S,Navy top-secret weapon
D) a new way to look into the behavior of blue whales
32,The underwater listening system was originally designed ________.
A) to trace and locate enemy vessels
B) to monitor deep-sea volcanic eruptions
C) to study the movement of ocean currents
D) to replace the global radio communications network
33,The deep-sea listening system makes use of ________.
A) the sophisticated technology of focusing sounds under water
B) the capability of sound to travel at high speed
C) the unique property of layers of ocean water in transmitting sound
D) low-frequency sounds traveling across different layers of water
34,It can be inferred from the passage that ________.
A) new radio devices should be developed for tracking the endangered blue whales
B) blue whales are no longer endangered with the use of the new listening system
C) opinions differ as to whether civilian scientists should be allowed to use military technology
D) military technology has great potential in civilian use
35,Which of the following is true about the U.S,Navy underwater listening network?
A) It is now partly accessible to civilian scientists.
B) It has been replaced by a more advanced system.
C) It became useless to the military after the cold war.
D) It is indispensable in protecting endangered species.
Passage Four
Questions 36 to 40 are based on the following passage.
The fitness movement that began in the late 1960s and early 1970s centered around aerobic exercise (有氧操),Millions of individuals became engaged in a variety of aerobic activities,and literally thousands of health spas developed around the country to capitalize (获利) on this emerging interest in fitness,particularly aerobic dancing for females,A number of fitness spas existed prior to this aerobic fitness movement,even a national chain with spas in most major cities,However,their focus was not on aerobics,but rather on weight-training programs designed to develop muscular mass,strength,and endurance in their primarily male enthusiasts,These fitness spas did not seem to benefit financially form the aerobic fitness movement to better health,since medical opinion suggested that weight-training programs offered few,if any,health benefits,In recent years,however,weight training has again become increasingly popular for males and for females,Many current programs focus not only on developing muscular strength and endurance but on aerobic fitness as well.
Historically,most physical-fitness tests have usually included measures of muscular strength and endurance,not for health-related reasons,but primarily because such fitness components have been related to performance in athletics,However,in recent years,evidence has shown that training programs designed primarily to improve muscular strength and endurance might also offer some health benefits as well,The American College of Sports Medicine now recommends that weight training be part of a total fitness program for healthy Americans,Increased participation in such training is one of the specific physical activity and fitness objectives of Healthy People 2000,National Health Promotion and Disease Prevention Objectives.
36,The word,spas” (Line 3,Para,1) most probably refers to ________.
A) sports activities
B) places for physical exercise
C) recreation centers
D) athletic training programs
37,Early fitness spas were intended mainly for ________.
A) the promotion of aerobic exercise
B) endurance and muscular development
C) the improvement of women’s figures
D) better performance in aerobic dancing
38,What was the attitude of doctors towards weight training in health improvement?
A) Positive.
B) Indifferent.
C) Negative.
D) Cautious.
39,People were given physical fitness tests in order to find out ________.
A) how ell they could do in athletics
B) what their health condition was like
C) what kind of fitness center was suitable for them
D) whether they were fit for aerobic exercise
40,Recent studies have suggested that weight training ________.
A) has become an essential part of people’s life
B) may well affect the health of the trainees
C) will attract more people in the days to come
D) contributes to health improvement as well
Part III Vocabulary and Structure (20 minutes)
Directions,There are 3.0,incomplete sentences in this part,For each sentence there are four choices marked A),B),C) and D),Choose the ONE that best completes the sentence,Then mark the corresponding letter on the Answer Sheet with a single line through the center.
41,You would be ________ a risk to let your child go to school by himself.
A) omitting
B) attaching
C) affording
D) running
42,He is always here; it’s ________ you’ve never met him.
A) unique
B) strange
C) rare
D) peculiar
43,There has been a great increase in retail sales,________?
A) does there
B) isn’t there
C) hasn’t there
D) isn’t it
44,We’d like to ________ a table for five for dinner this evening.
A) preserve
B) retain
C) reserve
D) sustain
45,Although a teenager,Fred could resist ________ what to do and what not to do.
A) being told
B) telling
C) to be told
D) to tell
46,The European Union countries were once worried that they would not have ________ supplies of petroleum.
A) proficient
B) efficient
C) potential
D) sufficient
47,In fact,Peter would rather have left for San Francisco than ________ in New York.
A) to stay
B) stayed
C) staying
D) having stayed
48,He soon received promotion,for his superiors realized that he was a man of considerable ________.
A) ability
B) future
C) possibility
D) opportunity
49,Britain ahs the highest ________ of road traffic in the world—over 60 cars for every mile of road.
A) popularity
B) density
C) intensity
D) prosperity
50,How is it ________ your roommate’s request and yours are identical?
A) if
B) so
C) what
D) that
51,In my opinion,he’s ________ the most imaginative of all the contemporary poets.
A) in all
B) at best
C) for all
D) by far
52,He didn’t have time to read the report word for word,he just ________ it.
A) skimmed
B) observed
C) overlooked
D) glanced
53,The leader of the expedition ________ everyone to follow his example.
A) promoted
B) reinforced
C) sparked
D) inspired
54,What a lovely party! It’s worth ________ all my life.
A) remembering
B) to remember
C) to be remembered
D) being remembered
55,Who would you rather ________ with you,George or me?
A) going
B) to go
C) have gone
D) went
56,The ________ goal of the book is to help bridge the gap between research and teaching,particularly between researchers and teachers.
A) intensive
B) concise
C) joint
D) overall
57,The owner and editor of the newspaper ________ the conference.
A) were attending
B) were to attend
C) is to attend
D) are to attend
58,We left the meeting,there obviously ________ no point in staying.
A) were
B) being
C) to be
D) having
59,Their products are frequently overpriced and ________ in quality.
A) influential
B) inferior
C) superior
D) subordinate
60,The neighborhood boys like to play basketball on that ________ lot.
A) valid
B) vacant
C) vain
D) vague
61,These people once had fame and fortune; now ________ is left to them is utter poverty.
A) all that
B) all what
C) all which
D) that all
62,To our ________,Geoffrey’s illness proved not to be as serious as we had feared.
A) anxiety
B) relief
C) view
D) judgment
63,Many people like white color as it is a ________ of purity.
A) symbol
B) sign
C) signal
D) symptom
64,The residents,________ had been damaged by the fire,were given help by the Red Cross.
A) all of their homes
B) all their homes
C) whose all homes
D) all of whose homes
65,This research has attracted wide ________ coverage and has featured on BBC television’s Tomorrow’s World.
A) message
B) information
C) media
D) data
66,I would never have ________ a court of law if I hadn’t been so desperate.
A) sought for
B) accounted for
C) turned up
D) resorted to
67,Investigators agreed that passengers on the airliner ________ at the very moment of the crash.
A) should have died
B) must be dying
C) must have died
D) ought to die
68,The energy ________ by the chain reaction is transformed into heat.
A) transferred
B) released
C) delivered
D) conveyed
69,________ their work will give us a much better feel for the wide differences between the two schools of thought.
A) To have reviewed
B) Having reviewed
C) Reviewing
D) Being reviewed
70,During the process,great care has to be taken to protect the ________ silk from damage.
A) sensitive
B) tender
C) delicate
D) sensible
Part IV Short Answer Questions (15 minutes)
Directions,In this part there is a short passage-with five questions or incomplete statements,Read the passage carefully,Then answer the questions or complete the statements in the fewest possible words (not exceeding 10 words).
As researchers learn more about how children’s intelligence develops,they are increasingly surprised by the power of parents,The power of the school has been replaced by the home,To begin with,all the factors which are part of intelligence—the child’s understanding of language,learning patterns,curiosity—are established well before the child enters school at the age of six,Study after study has shown that even after school begins,children’s achievements have been far more influenced by parents than by teachers,This is particularly true about learning that is language-related,The school rather than the home is given credit for variations in achievement in subjects such as science.
In view of their power,it’s sad to see so many parents not making the most of their child’s intelligence,Until recently parents had been warned by educators who asked them not to educate their children,Many teachers now realize that children cannot be educated only at school and parents are being asked to contribute both before and after the child enters school.
Parents have been particularly afraid to teach reading at home,Of course,children shouldn’t be pushed to read by their parents,but educators have discovered that reading is best taught individually—and the easiest place to do this is at home,Many four-and five-year-olds who have been shown a few letters and taught their sounds will compose single words of their own with them even before they have been taught to read.
Questions,(注意：答题尽量简短，超过10个词要扣分。每条横线限写一个英语单词，标点符号不占格)
S1,What have researchers found out about the influence of parents and the school on children’s intelligence?
S2,What do researchers conclude about children’s learning patterns?
S3,In which area may school play a more important role?
S4,Why did many parents fail to make the most of their children’s intelligence?
S5,The author suggests in the last paragraph that parents should be encouraged to
Part V Writing (30 minutes)
Directions,For this part,you are allowed thirty minutes to write a composition on the topic Student Use of Computers,You should write at least 120 words,and base your composition on the chart and the outline given below:
1,上图所示为1990年、1995年、2002年某校大学生使用计算机的情况，请描述其变化；
2,请说明发生这些变化的原因(可从计算机的用途、价格或社会发展等方面加以说明)；
3,你认为目前大学生在计算机使用中有什么困难或问题。
Student Use of Computers
答案
Part I
1,D 2,A 3,A 4,D 5,B
6,C 7,A 8,D 9,D 10,A
11,C 12,D 13,C 14,B 15,B
16,C 17,A 18,A 19,C 20,D
Part II
21,C 22,A 23,A 24,D 25,C
26,B 27,D 28,C 29,A 30,B
31,B 32,A 33,C 34,D 35,A
36,B 37,B 38,C 39,A 40,D
Part III
41,D 42,B 43,C 44,B 45,A
46,D 47,B 48,A 49,B 50,D
51,D 52,A 53,D 54,A 55,D
56,D 57,C 58,B 59,B 60,C
61,A 62,B 63,A 64,D 65,C
66,D 67,C 68,B 69,C 70,C
S1,Parents have greater influence than the school./Parent’s influence is greater than the school’s.
S2,They are established well before the age of six.
S3,Science subjects.
S4,They were told by educators not to educate their children.
S5,teach reading at home.
2002年6月四级听力原文
1,W,I suppose you’ve bought some gifts for your family.
M,Well,I’ve bought a shirt for my father and two books for my sister,But I haven’t decided what to buy for my mother probably some jewels.
Q,Who did the man buy the books for?
2,W,Look,it says they want a junior sales manager and it seems like it’s a big company,That’ll be good for you might have to travel a lot.
M,Do they say anything about the experience?
Q,What are they talking about?
3,W,I think we’ve covered everything,What about a cup of coffee before we move onto the next item?
M,Good idea,I really can’t wait another minute.
Q,What does the woman suggest doing?
4,W,But what happens if it rains,What are we going to do then?
M,We’ll have to count on good weather,But if it does rain the whole thing will have to be canceled.
Q,What do we learn from the conversation?
5,W,You took an optional course this semester didn’t you? How is it going?
M,Terrible,It seems like the more the professor talks the less I understand.
Q,How does the man feel about the course?
6,W,Mark is playing computer games.
M,Should he do that when the final exam is drawing near?
Q,What does the man think Mark should do?
7,M,Jack seems to think this year’s basketball season will be disappointing.
W,That’s his opinion,Most others think differently.
Q,What does the woman mean?
8,M,Is this the check-in counter for Flight 914 to Los Angeles?
M,Yes,but I’m sorry the flight is delayed because of a minor mechanical problem,Please wait for further notice.
Q,What do we learn from this conversation?
9,M,Excuse me,I’d like to place an advertisement for a used car in this Sunday edition of your paper.
W,Ok,but you have to run your advertisement all week,We can’t quote rates for just Sunday.
Q,Where is the conversation most probably taking place?
10,M,I spend so much time polishing my letter application.
W,It’s worthwhile to make the effort,You know just how important it is to give impression.
Q,What do we know about the man?
Passage One
Not everybody reads the daily newspaper,People who don’t read newspaper are sometimes referred to as non-readers,Early research has shown that the non-readers are generally low in education low in income either very young or very old,In addition non-readers are more likely to live in rural areas and have less contact with neighbours and friends,Other studies show that non-readers tend to isolate themselves from the community and less likely to own a home and seldom belong to local voluntary organizations
Why don’t these people read daily paper? They say they don’t have the time they prefer radio or TV they have no interest in reading a tale and besides they think newspapers are too expensive,Recent surveys however,have indicated the portrait of the non-reader is more complicated than first thought,There appears to be a group of non-readers that do not fit the type mentioned above,They are high in income and fall into the age group of 26 to 65,They are far move likely to report that they don’t have the time to read the papers and they have no interest in the content,Editors and publishers are attempting to win them back,First they are also adding news briefs and comprehensive indexes,This will help overcome the time problem,And they are also giving variety to newspaper content to help build the reader’s interest.
Questions 11 to 13 are based on the passage you have just heard.
11,What is typical of non-readers according to early research?
12,What are the finds of recent surveys?
13,What are editors and publishers doing to attract the non-readers?
Passage Two
Did you know that there’s a kind of bird that can sew? This called the tailor bird uses its mouth as a needle,It sews leaves together in the shape of a cup then it adds a layer of straw to the inside of the cup and lays its eggs there,Each bird species builds its own special kind of nest,The most common materials used for nests are grasses branches and feathers,A bird must weave these materials into a nest,Just imagine building a house without cement or nails to hold together.
Another bird is called the weaver bird,The weaver bird builds a nest that looks like a basket the nest shaped like a pear with a hole in the middle,The hole is the door of the nest,A third bird is called the oven bird,The oven bird makes a nest that is very solid,The nest is made of mud,The oven bird forms the mud into the shape of an oven and then let it dry in the sun,The sun bakes the mud making it very hard,Not all birds make their homes in branches,Some birds build their nests on the ground while others bury their eggs under the ground,And some birds do not build nests at all,So when you look for nests and eggs in branches of the trees and bushes remember that some nests may be right your feet.
Questions 14 to 17 are based on the passage you have just heard.
14,What does the nest built by tailor bird look like?
15,Why is there a hole in the weaver bird’s nest?
16,What is the oven bird’s nest made of?
17,What might surprise us about birds’ nests according to the speaker?
Passage Three
You can tell the age of a tree by counting its rings but these records of trees’ life really say a lot more,Scientists are using tree rings to learn what’s being happening on the sun’s surface for the last ten thousand years,Each ring represents a year of growth,As the tree grows it adds a layer to its trunk taking up chemical elements from the air,By looking up the elements in the rings for a given year scientists can tell what elements were in the air that year,Doctors Stevenson is analysing one element—carbon-14 in ring from both living and dead trees,Some of the rings go back almost ten thousand years to the end of the Ice Age,When Stevenson followed the carbon-14 trail back in time he found carbon-4 levels change with the intensity of solar burning,You see the sun has cycles,Sometimes it burns fiercely and other times it’s relatively calm,During the sun’s violent periods it throws off charged particles in fast moving strings called solar winds,The particles interfere with the formation of carbon-14 on earth,When there’s more solar wind activity less carbon-14 is produced,Ten thousand years of tree rings show that the carbon-14 level rises and falls about every 420 years,The scientists concluded that the solar wind activity must follow the same cycle.
Questions 18 to 20 are based on the passage you have just heard.
18,What is the purpose of the scientists in studying tree rings?
19,What affects the amount of carbon-14 on earth?
20,What do we learn from the passage about the solar wind activity?
