大学英语四级考试15选10专项训练(五)

遇见明天

UNIT 21

   Like most parents, geologistBrain Atwater worries about his daughter's safety. But these days, he has anunusual concern; The public school she11 in Seattle has unreinforcedbrick walls, a 12 being easy to collapse during earthquakes. The same 13of walls crushed hundreds of thousands of people during the 1976 Tangshan quake in China.

  A decade ago, Atwater would have paid little notice toschoolroom walls. But over the last several years, he and other scientists havefound 14 signs that the Pacific Northwesthas experienced giant quakes in the distant past and that the area may beheaded for a destructive shock in the near future.

  At a meeting of the AmericanGeophysical Union in December, researchers discussed the 15 uncoveredevidence of quake potential in the Pacific Northwest.While some remain unconvinced that huge earthquakes—with magnitudes of 8 orhigher—do indeed 16 this region, a growing number consider such shocks aserious possibility.

  What's worrisome, they say, isthat northwestern cities such as Portland, Seattle and Vancouver havenot prepared for earthquakes of this magnitude, which could shake the region's 17centers with enough force to make the recent San Francisco area damage seem 18 incomparison.

  "I think it's quite true tosay that nothing has really been designed with one of these earthquakes inmind," says seismologist Paul Somerville of Woodward. At the meeting,Somerville and his colleagues 19 estimates of the degree of shaking. Portland and Seattlewould suffer during such a 20earthquake.

A. massive B. recently C. construction    D. displayed

E. relatively     F.  attends  G. type   H. strike

I. structure  J.  participates     K. excessive   L.  mild

M. disturbing   N. population  0.  presented        

Unit Twenty-Two

Passage 2

  During the nineteenth andtwentieth centuries, migrations have taken place within 11 countries;the cities with their industries have attracted people away from the country.The possibility of earning a fixed 12 in a factory or office was more attractive than the possibilityof staying on the farm and having one's work 13 by frost, storms, or droughts.Furthermore,    the development ofagricultural machinery made it possible for fewer people to do the same 14of work.     

  Thus, at the same time when theindustrial revolution made it possible to produce goods more 15 and morequickly in factories, agricultural revolution also took place. Instead ofleaving fields empty every third year, farmers began to plant clover or someother crop that would 16 the soil.   

  Instead of using only animalfertilizer, farmers began to use chemical fertilizers to keep the soil• 150•rich.  

  These methods have enabled Frenchfarmers,  for example,  to get five times as much wheat as was 17from the same land two centuries ago.

  In many countries farmers find itmore 18 to raise only one crop or one kind of animal. They choose thekind that gives the best results. Then they sell all that they produce, insteadof trying to grow a little of everything and consume what they grow. This is amore feasible type of 19 because modern methods and machinery areadapted to specific animals and specific crops. Therefore, it would be tooexpensive to do all the work by hand, or to buy the 20 needed forseveral different kinds of farming.

A. salary    E.  deserted    I.equivalent     M. destroyed

B. freely      F. operation    J.  enrich      N. certain

C. profitable   G.amount       K. fruitful        O.  cheaply

D. obtained     H.payment     L. equipment

Unit Twenty-Three

Passage 2

  The difference between a liquidand a gas is obvious under the conditions of temperature and pressure commonlyfound at the surface of the Earth. A liquid can be kept in an open containerand fill it to the level of a free surface. A gas forms no free surface buttends to diffuse throughout the 11 available; it must therefore be keptin a closed container or held by a gravitational field, as in the 12 ofa planet's atmosphere.

  The distinction was a 13feature of early theories describing the phases of matter. In the nineteenthcentury, for example, one theory maintained that a liquid could be"dissolved" in a vapor without losing its identity, and anothertheory 14 that the two phases are made up of different kinds of molecules.

  The theories now prevailing take aquite different approach by emphasizing what liquids and gases have in 15 Theyare both forms of matter that have no 16 structure, and they both flowreadily.

  The fundamental similarity ofliquids and gases becomes clearly apparent when the temperature and pressureare 17 somewhat. Suppose a closed container 18 filled with aliquid is heated.

  The liquid expands, or in otherwords becomes less dense; some of it evaporates. In contrast, the vapor abovethe liquid surface becomes denser as the evaporated molecules are 19 toit. The combination of temperature and pressure at which the densities become20 is called the critical point.

A. added    B. case    C. prominent   D. held

E. equal F. partially    G. example    H. previous

I. space J, lifted   K. permanent   L.     particularly

M.extended    N.  raised  O.    common         

Unit Twenty-Four

Passage 2

  Scientists at Sussex Universityappear to be on the way to 11 how the mosquito, carrier of diseases suchas malaria and yellow fever, homes in on its target. The problem is that theyhave found that the best way to avoid being bitten is: stop breathing, stopsweating, and keep down the temperature of your immediate surroundings. 12the first suggestion is impossible and the others very difficult.

  Scientists have found that thereare three 13 stages in a mosquito's assault. Stage one is at fifty feetaway, when the insect first smells a man or a animal to 14 . Stage twois thought to come into operation about twenty-five feet from the target, whenthe insect becomes guided by the carbon dioxide breathed out by the intendedvictim. Stage three is when the mosquito is only a matter of inches from its 15the warmth and moisture given off by the victim is the final clue.

  The researchers then * 16how repellents interfere with its three-stage attack. They found repellents actmore subtly than by just giving off a nasty smell. A Canadian researcher saysthat repellents appear to 17 mosquitoes first when it is following thecarbon dioxide and second during the final approach, where the warmth andmoisture are the insect's 18 .

Air pervaded by one of the many chemical repellents stops the mosquitoreacting to the victim's carbon dioxide, and the repellent seems to affect thetiny hairs with which the insect senses moisture in the air. The sensors areblocked so that the 19  does notknow whether it is flying through a moist current, or the sensors are made tosend the 20 signals.

A.examined   B. animal   C. wrong    D. insect

E. bite    F.  Unfortunately  G. inventing    H. distinct

I. prey    J.  guide     K. checked  L.     definite

M.Unnecessarily  N.    confuse     O. discovering     

Unit Twenty-Five

Passage 2

  Climate, more than any othersingle factor, 11 the distribution of life on Earth. Climatic boundariesestablish the limits within which organisms can survive. Plants, even more thananimals, must be 12 adapted to climate in order to survive.  

  They cannot move about or takeshelter but must be equipped to 13 whatever weather conditions arelikely to occur. In the harsh conditions of the far north of the earth, forexample, low growing mosses, lichens, and a few flowering plants all hold tothe ground for shelter from icy winds.

  Animals, despite their 14to move about and find shelter, are just as much influenced by climate asplants are. Creatures such as the camel and the penguin are so highlyspecialized that they have an 15 limited distribution. Others, such asbears, are flexible enough to adapt to a 16 range of climates..Ocean-dwelling organisms are just as sensitive to climatic changes—in this casetemperature and salinity—as land animals.     

  Reef corals can survive only inclear warm seawater. Certain for a minarets are so sensitive to changes intheir 17 that their presence can be taken as an 18 of seatemperature. Human beings are among the 19 specialized of all animalsand can live almost anywhere.  

  Their clothes and their homes 20as a sort of "miniature climate" that can be taken with themeverywhere.

A. least  B. determines c.  ability    D. urgently

E. broad     F.  behave  G. worst     H. index

I. endure     J.  extremely   K. entertain   L.  well

M. neighborhood     N. act     O. environment         

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