2013年英语四级阅读试题及答案2

　　Research by the University of Exeter1 has revealed that ants have a big impact on their local environment as a result of their activity as "ecosystem engineers" and predators(食肉动物). The study, published in the Journal of Animal Ecology, found that ants have two distinct(显著的)effects on their local environment.

　　Firstly, through moving of soil by nest building2 activity and by collecting food they affect the level of nutrients(营养物)in the soil. This can indirectly impact the local populations of many animal groups, from decomposers(腐生物,分解体)to species much higher up the food chain.

　　Secondly, they prey(捕食) on a wide range of other animals, including larger prey which can be attacked by vast numbers of ant workers.

　　Dirk Sanders, an author of the study from the university’s Centre for Ecology and Conservation, said: "Ants are very effective predators which thrive in huge numbers. They’re also very territorial3 and very aggressive, defending their resources and territory against other predators. All of this means they have a strong influence on their surrounding area."

　　"In this research, we studied for the first time how big this impact is and the subtleties(微妙) of it. What we found is that despite being predators, their presence can also lead to an increase in density and diversity of other animal groups4. They genuinely play a key role in the local environment, having a big influence on the grassland food web," Sanders said.

　　The study, carried out in Germany, studied the impact of the presence of different combinations and densities of black garden ants and common red ants, both species which can be found across Europe, including in the UK. It found that a low density of ants in an area increased the diversity and density of other animals in the local area, particularly the density of herbivores(食草动物) and decomposers. At higher densities ants had no or the opposite effect, showing that predation is counteracting the positive influence.

　　Dr Frank van Veen, another author on the study, said: "What we find is that the impact of ants on soil nutrient levels has a positive effect on animal groups at low levels, but as the number of ants increases, their predatory impacts have the bigger effect — thereby counteracting the positive influence via ecosystem engineering."

　　Ants are important components of ecosystems not only because they constitute a great part of the animal biomass5 (生物量) but also because they act as ecosystem engineers. Ant biodiversity6(生物多样性)is incredibly high and these organisms are highly responsive(敏感的，易受影响的) to human impact, which obviously reduces its richness. However, it is not clear how such disturbance damages the maintenance of ant services to the ecosystem7.Ants are important in below ground processes8 through the alteration of the physical and chemical environment and through their effects on plants, microorganisms, and other soil organisms

　　The standardized educational or psychological tests, which are widely used to aid in selecting, assigning or promoting students, employees and military personnel, have been the target of recent attacks in books, magazines, the daily press, and even in Congress. The target is wrong, for, in attacking the tests, critics divert attention from the fault that lies with ill-informed or incompetent users. The tests themselves are merely tools. Whether the results will be valuable, meaningless, or even misleading depends partly upon the tool itself but largely upon the user.

　　All informed predictions of future performance are based upon some knowledge of relevant past performance. How well the predictions will be validated by later performance depends upon the amount, reliability and appropriateness of the information used and on the skill and wisdom with which it is interpreted. Anyone who keeps careful score knows that the information available is always incomplete and that the predictions are always subject to error.

　　Standardized tests should be considered in this context: they provide a quick, objective method of getting some kind of information about what a person has learned, the skills he has developed, or the kind of person he is. The information so obtained has, qualitatively, the same advantages and shortcomings as other kinds of information. Whether to use tests, other kinds of information, or both in a particular situation depends, therefore, upon the empirical evidence concerning comparative validity and upon such factors as cost and availability.

　　In general, the tests work most effectively when the traits or qualities to be measured can be most precisely defined ( for example, ability to do well in a particular course of training program ) and least effectively when what is to be measured or predicted cannot be well defined, for example, personality or creativity. Properly used, they provide a rapid means of getting comparable information about many people. Sometimes they identify students whose high potential has not been previously recognized.

　　The modern sailing ship was developed by a man who never went to sea.

　　He was Prince Henry of Portugal,the younger son of the Partuguese king and an English princess.?

　　Prince Henry lived in the fifteenth century.As a boy he became devoted to the sea,and he dedicated himself to improving the design of ships and the methods of sailing them.In 1416,when he was twenty?two,Henry founded a school for mariners, to which he invited everyone who could help him—Jewish astronomers,Italian and Spanish sailors, and Arab mathematicians and map makers who knew to use the crude

　　compass of the day and could improve it.?

　　Henry’s goal was to design and equip vessels that would be capable of making long ocean voyages without having to hug the shore.The caravel carried more sail and was longer and slimmer than any ship then made,yet was tough enough to withstand gales at sea.He also developed the carrack,which was a slower ship,but one that was capable of carrying more cargo.

　　To Prince Henry the world owes credit for development of craft that made oceanic exploration possible.He lives in history as Henry the Navigator.

　　The modern sailing ship was developed by a man who never went to sea.

　　He was Prince Henry of Portugal,the younger son of the Partuguese king and an English princess.?

　　Prince Henry lived in the fifteenth century.As a boy he became devoted to the sea,and he dedicated himself to improving the design of ships and the methods of sailing them.In 1416,when he was twenty?two,Henry founded a school for mariners, to which he invited everyone who could help him—Jewish astronomers,Italian and Spanish sailors, and Arab mathematicians and map makers who knew to use the crude

　　compass of the day and could improve it.?

　　Henry’s goal was to design and equip vessels that would be capable of making long ocean voyages without having to hug the shore.The caravel carried more sail and was longer and slimmer than any ship then made,yet was tough enough to withstand gales at sea.He also developed the carrack,which was a slower ship,but one that was capable of carrying more cargo.

　　To Prince Henry the world owes credit for development of craft that made oceanic exploration possible.He lives in history as Henry the Navigator.

　　 Now let us look at how we read. When we read a printed text, our eyes move across a page in short, jerky movement. We recognize words usually when our eyes are still when they fixate. Each time they fixate, we see a group of words. This is known as the recognition span or the visual span. The length of time ofr which the eyes stop ---the duration of the fixation ----varies considerably from person to person. It also vaies within any one person according to his purpose in reading and his familiarity with the text. Furthermore, it can be affected by such factors as lighting and tiredness.

　　Unfortunately, in the past, many reading improvement courses have concentrated too much on how our eyes move across the printed page. As a result of this misleading emphasis on the purely visual aspects of reading, numerous exercises have been devised to train the eyes to see more words at one fixation. For instance, in some exercises, words are flashed on to a screen for, say, a tenth or a twentieth of a second. One of the exercises has required students to fix their eyes on some central point, taking in the words on either side. Such word patterns are often constructed in the shape of rather steep pyramids so the reader takes in more and more words at each successive fixation. All these exercises are very clever, but it’s one thing to improve a person’s ability to see words and quite another thing to improve his ability to read a text efficiently. Reading requires the ability to understand the relationship between words. Consequently, for these reasons, many experts have now begun to question the usefulness of eye training, especially since any approach which trains a person to read isolated words and phrases would seem unlikely to help him in reading a continuous text