[外语类试卷]大学英语六级模拟试卷609及答案与解析.doc

1、大学英语六级模拟试卷 609及答案与解析 一、 Part I Writing (30 minutes) 1 For this part, you are allowed 30 minutes to write a composition on the topic How to Keep Psychologically Healthy? You should write at least 150 words, and base your composition on the outline given below in Chinese: 1心理健康问题往往是导致疾病的原因 2分析人们产生心理健康

2、问题的原因 (可从失业、压力过重、缺少支持、缺乏人际交往能力等方面加以分析 ) 3你认为人们应如何保持心理健康 How to Keep Psychologically Healthy? 二、 Part II Reading Comprehension (Skimming and Scanning) (15 minutes) Directions: In this part, you will have 15 minutes to go over the passage quickly and answer the questions attached to the passage. For q

3、uestions 1-4, mark： Y (for YES) if the statement agrees with the information given in the passage; N (for NO) if the statement contradicts the information given in the passage; NG (for NOT GIVEN) if the information is not given in the passage. 2 Population Growth Rates Populations have a birth rate

4、(the number of young produced per unit of population per unit of time), a death rate(the number of deaths per unit of time), and a growth rate. The major agent of population growth is births, and the major agent of population loss is deaths. When births exceed deaths, a population increases; and whe

5、n deaths exceed additions to a population, it decreases. When births equal deaths in a given population, its size remains the same, and it is said to have zero population growth. When introduced into a favorable environment with an abundance of resources, a small population may undergo geometric, or

6、 exponential(指数的 ) growth, in the manner of compound interest. Many populations experience exponential growth in the early stages of colonizing a habitat because they take over an underexploited niche or drive other populations out of a profitable one. Those populations that continue to grow exponen

7、tially, however, eventually reach the upper limits of the resources; they then decline sharply because of some catastrophic(灾难的 ) events such as starvation, disease, or competition from other species. In a general way, populations of plants and animals that characteristically experience cycles of ex

8、ponential growth are species that produce numerous young, provide little in the way of parental care, or produce an abundance of seeds having little food reserves. These species, usually short-lived, disperse rapidly and are able to colonize harsh or disturbed environments. Such organisms are often

9、called opportunistic species. Other populations tend to grow exponentially at first, and then logisticallythat is, their growth slows as the population increases, then levels off as the limits of their environment or carrying capacity are reached. Through various regulatory mechanisms, such populati

10、ons maintain something of an equilibrium(平衡 ) between their numbers and available resources. Animals exhibiting such population growth tend to produce fewer young but do provide them with parental care; the plants produce large seeds with considerable food reserves. These organisms are long-lived, h

11、ave low dispersal rates, and are poor colonizers of disturbed habitats. They tend to respond to changes in population density (the number of organisms per unit area) through changes in birth and death rates rather than through dispersal. As the population approaches the limit of resources, birth rat

12、es decline, and mortality of young and adults increases. Community Interactions Major influences on population growth involve various population interactions that tie the community together. These include competition, both within a species and among species; predation(掠夺行为 ), including parasitism(寄生

13、状态 ); and co-evolution, or adaptation. 1. Competition When a shared resource is in short supply, organisms compete, and those that are more successful survive. Within some plant and animal populations, all individuals may share the resources in such a way that none obtains sufficient quantities to s

14、urvive as adults or to reproduce. Among other plant and animal populations, dominant individuals claim access to the scarce resources and others are excluded. Individual plants tend to claim and hold onto a site until they lose vigor or die. These prevent other individuals from surviving by controll

15、ing light, moisture, and nutrients in their immediate areas. Many animals have a highly developed social organization through which resources such as space, food, and mates are apportioned among dominant members of the population. Such competitive interactions may involve social dominance, in which

16、the dominant individuals exclude subdominant individuals from the resource; or they may involve territoriality, in which the dominant individuals divide space into exclusive areas, which they defend. Subdominant or excluded individuals are forced to live in poorer habitats, do without the resource,

17、or leave the area. Many of these animals succumb to starvation, exposure, and predation. Competition among members of different species results in the division of resources in a community. Certain plants, for example, have roots that grow to different depths in the soil. Some have shallow roots that

18、 permit them to use moisture and nutrients near the surface. Others growing in the same place have deep roots that are able to exploit moisture and nutrients not available to surface-rooted plants. 2. Predation One of the fundamental interactions is predation, or the consumption of one living organi

19、sm, plant or animal, by another. While it serves to move energy and nutrients through the ecosystem, predation may also regulate population and promote natural selection by weeding the unfit from a population. Thus, a rabbit is a predator on grass, just as the fox is a predator on the rabbit. Predat

20、ion on plants involves defoliation(落叶 ) by grazers and the consumption of seeds and fruits. The abundance of plant predators, or herbivores, directly influences the growth and survival of the carnivores(食肉类 ). Thus, predator-prey interactions at one feeding level influence the predatorprey relations

21、 at the next feeding level. In some communities, predators may so reduce populations of prey species that a number of competing species can coexist in the same area because none is abundant enough to control the resource. When predators are reduced or removed, however, the dominant species tend to c

22、rowd out other competitors, thereby reducing species diversity. 3. Parasitism Closely related to predation is parasitism, wherein two organisms live together, one drawing its nourishment at the expense of the other Parasites(寄生虫 ), which are smaller than their hosts, include many viruses and bacteri

23、a. Because of this dependency relationship, parasites normally do not kill their hosts the way predators do. As a result, hosts and parasites generally coevolve(共同进行 ) a mutual tolerance, although parasites may regulate some host populations, lower their reproductive success, and modify behavior. 4.

24、 Coevolution Coevolution is the joint evolution of two unrelated species that have a close ecological relationshipthat is, the evolution of one species depends in part on the evolution of the other. Coevolution is also involved in predator-prey relations. Over time, as predators evolve more efficien

25、t ways of capturing or consuming prey, the prey evolves ways to escape predation. Plants have acquired such defensive mechanisms as thorns, spines, hard seed-coats, and poisonous or ill-tasting sap that deter would be consumers. Some herbivores(草食动物 ) are able to breach these defenses and attack the

26、 plant. Certain insects, such as the monarch butterfly, can incorporate poisonous substances found in food plants into their own tissues and use them as a defense against predators. Other animals avoid predators by assuming an appearance that blends them into the background or makes them appear part

27、 of the surroundings. The chameleon is a well-known example of this interaction. Some animals possessing obnoxious odors or poisons as a defense also have warning colorations, usually bright colors or patterns, that act as further warning signals to potential predators. Another coevolutionary relati

28、onship is mutualism, in which two or more species depend on one another and cannot live outside such an association. An example of mutualism(互利共生 ) is mycorrhizae, an obligatory relationship between fungi and certain plant roots. In one group, called ectomycorrhizae, the fungi form a cap or mantle a

29、bout the rootlets. The fungal hyphae(threads) invade the rootlet and grow between the cell walls as well as extending outward into the soil from the rootlet. The fungi, which include several common woodland mushrooms, depend on the tree for their energy source. In return the fungi aid the tree in ob

30、taining nutrients from the soil and protect the rootlets of the tree from certain diseases. Without the mycorrhizae some groups of trees, such as conifers and oaks, cannot survive and grow. Conversely, the fungi cannot exist without the trees. 2 Populations have 3 agents, namely, a birth rate, a dea

31、th rate, and a growth rate. （ A） Y （ B） N （ C） NG 3 The major agents of population growth are births and deaths. （ A） Y （ B） N （ C） NG 4 A small population may undergo geometric, or exponential growth when introduced into a favorable environment. （ A） Y （ B） N （ C） NG 5 Animals can not survive some

32、catastrophic events such as starvation, disease, or competition from other species. （ A） Y （ B） N （ C） NG 6 The short-lived, rapidly dispersed species are often called _. 7 Birth rates decline, and mortality of young and adults increases when the population approaches_. 8 When a shared resource is i

33、n short supply, organisms compete, and those that _survive. 9 The abundance of plant predators, or herbivores, directly influences _. 10 Parasites, which are smaller than their hosts, include _. 11 Certain insects, such as the monarch butterfly, can incorporate poisonous substances found in food pla

34、nts into their own tissues and use them as _. Section A Directions: 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. （ A） The woman is the mans boss. （ B） The man is the womans husband. （ C） The woman is the headmaster of a school. （ D） The woman wants to know so

36、mething about a student. （ A） She suggests the man to go to a farther place to trim his hair. （ B） She offers to cut the mans hair herself at the price of 10. （ C） She tells the man a cheaper but busier place to have his hair cut. （ D） She used to trim her hair in a luxurious saloon. （ A） Encourage

37、them. （ B） Stop them immediately. （ C） Give some explanation. （ D） Leave them alone. （ A） The man was the only survivor of an air crash. （ B） People on board were frightened and tried to escape. （ C） The man has always been very lucky in accidents. （ D） A few passengers came back home safe and sound

38、. （ A） He was taking pictures of the campus. （ B） His photographs were on the evening news. （ C） He went to see a film on campus. （ D） His television appearance was unintentional. （ A） He didnt know the woman was late for work. （ B） He asked why the woman wasnt there on time. （ C） He doesnt have a h

39、abit of being on time, either. （ D） He wants the woman to keep a habit of being punctual. （ A） They both graduated from art schools. （ B） They majored in different areas of art. （ C） They are equally competent for the job. （ D） They are both willing to draw the posters. （ A） Public buses are fast an

40、d cheap. （ B） Parking is becoming a big problem. （ C） Buses and taxis are easy to find parking. （ D） People can find nowhere to park their cars. 20 What is the woman doing? （ A） Interviewing a movie star. （ B） Discussing teenage role models. （ C） Hosting a television show. （ D） Reviewing a new biogr

41、aphy. 21 Why did James Dean move back to Indiana when he was young? （ A） He lost his mother. （ B） He was unhappy in California. （ C） He missed his aunt. （ D） He had to attend school there. 22 What does the man say James Dean did at college in California? （ A） He delivered public speeches. （ B） He go

42、t seriously into acting. （ C） He hosted talk shows on TV. （ D） He played a role in East of Eden. 23 What do we know about James Dean from the conversation? （ A） He made numerous popular movies. （ B） He has long been a legendary figure. （ C） He was best at acting in Hollywood tragedies. （ D） He was t

43、he most successful actor of his time. （ A） North Dakota and Washington D.C （ B） South Dakota and Washington D.C （ C） Wisconsin and Wyoming. （ D） Wyoming and Washington. （ A） It is offered to anyone at any time. （ B） It is offered by post. （ C） It is only offered to people with disabilities. （ D） It

44、is offered regardless of the distance and the money. （ A） The more money goes into the campaign, the more democracy voters can enjoy. （ B） Too much money will result in a third party. （ C） Sufficient money may bridge the gap between the candidates and the voters. （ D） Too much money may hinder the v

45、oters from the candidates true ideas. （ A） The Campaign finance reform. （ B） Conflicts between the Democrats and the Republicans. （ C） The passing of a bill. （ D） A Voter Law. Section B Directions: In this section, you will hear 3 short passages. At the end of each passage, you will hear some questi

46、ons. 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. （ A） Scholarship. （ B） Language talent. （ C） Screening system. （ D） Scholastic ability. （ A） Learn the important aspect of American

47、 life. （ B） Bring returns back to his native land. （ C） Improve his language ability. （ D） Earn enough money to support his study. （ A） Become a member of the Committee for the Exchange of Foreign Students. （ B） Find the organization sponsoring him. （ C） Learn how to get accustomed to the life in th

48、e United States. （ D） Stay in a foreign country for six months. （ A） The meaning of facial expressions depends on situations. （ B） Facial expressions can cause misunderstanding across culture. （ C） People from one culture may lack facial expressions because they experience less emotion. （ D） Facial

49、expressions may disguise true feelings. （ A） They smile to cover embarrassment. （ B） It is an unusual and even suspicious behavior. （ C） They smile to show politeness. （ D） It is an expression of pleasure. （ A） We shouldnt judge people by reading their faces. （ B） We shouldnt smile in the wrong place. （ C） We shouldnt cover our true feelings. （ D） We shouldnt express our emotions too openly. （ A） A research on space. （ B） An event of imagination. （ C） A historic discovery. （ D） A scientific adventure. （ A）