Even plant can run a fever, especially when they’re under attack by insects or disease. But unlike human, plants can have their temperature taken from 3, 000 feet away - straight up. A decade ago, adopting the infrared （红外线）scanning technology developed for military purposes and other satellites, physicist Stephen Paley came up with a quick way to take the temperature of crops to determine which ones are under stress. The goal was to let farmers precisely target pesticide （杀虫剂）spraying rather than rain poison on a whole field, which invariably includes plants that don’t have pest （害虫）problems.
　　Even better, Paley’s Remote Scanning Services Company could detect crop problems before they became visible to the eye. Mounted on a plane flown at 3, 000 feet at night, an infrared scanner measured the heat emitted by crops. The data were transformed into a color - coded map showing where plants were running“ fevers”. Farmers could then spot - spray, using 50 to 70 percent less pesticide than they otherwise would.
　　The bad news is that Paley’s company closed down in 1984, after only three years. Farmers resisted the new technology and long - term backers were hard to find. But with the renewed concern about pesticides on produce, and refinements in infrared scanning, Paley hopes to get back into operation. Agriculture experts have no doubt the technology works. “This technique can be used on 75 percent of agricultural land in the United States, ” says George Oerther of Texas A & M. Ray Jackson , who recently retired from the Department of Agriculture, thinks remote infrared crop scanning could be adopted by the end of the decade. But only ff Paley finds the financial backing which he failed to obtain 10 years ago.
　56．Plants will emit an increased amount of heat when they are________.
　　A. sprayed with pesticides     B. facing an infrared scanner
　　C. in poor physical condition   D. exposed to excessive sun rays
　57．In order to apply pesticide spraying precisely, we can use infrared scanning to________.
　　A. estimate the damage to the crops    B. measure the size of the affected area
　　C. draw a color -coded map          D. locate the problem area
　58．Farmers can save a considerable amount of pesticide by________.
　　A. resorting to spot – spraying   B. consulting infrared scanning experts
　　C. transforming poisoned rain    D. detecting crop problems at an early stage
　59．The application of infrared scanning technology to agriculture met with some difficulties________.,
　　A. the lack of official support        B. its high cost
　　C. the lack of financial support      D. its failure to help increase production
　60．Infrared scanning technology may be brought back into operation because of________.
　　A. the desire of farmers to improve the quality of their produce
　　B. growing concern about the excessive use of pesticides on crops
　　C. the forceful promotion by the Department of Agriculture
　　D. full support from agricultural experts

　　Even plant can run a fever, especially when they’re under attack by insects or disease. But unlike human, plants can have their temperature taken from 3, 000 feet away - straight up. A decade ago, adopting the infrared （红外线）scanning technology developed for military purposes and other satellites, physicist Stephen Paley came up with a quick way to take the temperature of crops to determine which ones are under stress. The goal was to let farmers precisely target pesticide （杀虫剂）spraying rather than rain poison on a whole field, which invariably includes plants that don’t have pest （害虫）problems.

　　Even better, Paley’s Remote Scanning Services Company could detect crop problems before they became visible to the eye. Mounted on a plane flown at 3, 000 feet at night, an infrared scanner measured the heat emitted by crops. The data were transformed into a color - coded map showing where plants were running“ fevers”. Farmers could then spot - spray, using 50 to 70 percent less pesticide than they otherwise would.

　　The bad news is that Paley’s company closed down in 1984, after only three years. Farmers resisted the new technology and long - term backers were hard to find. But with the renewed concern about pesticides on produce, and refinements in infrared scanning, Paley hopes to get back into operation. Agriculture experts have no doubt the technology works. “This technique can be used on 75 percent of agricultural land in the United States, ” says George Oerther of Texas A & M. Ray Jackson , who recently retired from the Department of Agriculture, thinks remote infrared crop scanning could be adopted by the end of the decade. But only ff Paley finds the financial backing which he failed to obtain 10 years ago.

　56．Plants will emit an increased amount of heat when they are________.

　　A. sprayed with pesticides     B. facing an infrared scanner

　　C. in poor physical condition   D. exposed to excessive sun rays

　57．In order to apply pesticide spraying precisely, we can use infrared scanning to________.

　　A. estimate the damage to the crops    B. measure the size of the affected area

　　C. draw a color -coded map          D. locate the problem area

　58．Farmers can save a considerable amount of pesticide by________.

　　A. resorting to spot – spraying   B. consulting infrared scanning experts

　　C. transforming poisoned rain    D. detecting crop problems at an early stage

　59．The application of infrared scanning technology to agriculture met with some difficulties________.,

　　A. the lack of official support        B. its high cost

　　C. the lack of financial support      D. its failure to help increase production

　60．Infrared scanning technology may be brought back into operation because of________.

　　A. the desire of farmers to improve the quality of their produce

　　B. growing concern about the excessive use of pesticides on crops

　　C. the forceful promotion by the Department of Agriculture

　　D. full support from agricultural experts

D
　　In the atmosphere,carbon dioxide actd rather like a one-way mirror or the glass in the roof of a greenhouse which allows the sun's rays to enter but prevents the heat from excaping.
　　According to a weather expert's prediction,the atmosphere will be 3 warmer in the year 2050 than it is today, if man continues to burn luels at the present rate. If this warming up took place,the ice caps in the poles would begin to melt,thus raising sea level several meters and severely flooding coastal cities.Also，the increase in atmospheric temperature would lead to great changes in the climate of the northern hemisphere(半球),psooicbly resulting in an alteration of earth's chief food growing zones.
　　In the past,concern about a man - made warming of the earth has concentrated on the Arctic because the Antarctic is much colder and has a much thicker ice sheet.But the weather experts are now paying more attention to West Antarctic,which may be affected by a warming on the scale that will possibly take place in the next fifty years from on burning of fuels.
　　Satellite pictures showthat large areas of Antarctic ice are already disappearing.The evidence available suggests that a warming has taken place.This fits the theory that carbon dioxide warms the earth.
　　However,most of the fuel is burnt in the northern hemisphere,where temperatures seem to be falling.Scientists conclude,therefore,that up to now natural influences on the weather have exceeded those caused by man.The question is:Which natural cause has most effect on the weather?
　　One possibility is the variable behavior of the sun.Astronomers at one research station have studied the hot spots and cold spots(that is,the relatively less hot spots) on the sun. As the sun rotates(旋转),every 27.5 days,it presents hotter or colder faces to the earth,and different aspects to different parts of the earth.This seems to have a considerable effect on the distribution of the earth's atmospheric pressure,and consequently on wind circulation.The sun is also variable over a long term:its heat output goes up and down in cycles,the latest trend being downward.
　　Scientists are now finding mutual relations between models of solar weather interactions and the actual climate over many thousands of years ,including the last Ice Age.The problem is that the models are predicting that the world should be entering a new Ice Age and it is not.
　　One way of solving this theoretical difficulty is to assume a delay of thousands of years while the solar effects overcome the inertia(不活动，惰性) of the earth's climate.If this is right,the warming effect of carbon dioxide might thus be serving as a useful counter balance to the sun's diminishing heat.
　　68.It can be concluded that a concentration of carbon dioxide in the atmosphere would ___.
　　　A.mean a warming - up im the Arctic
　　　B.raise the temperature of the earth's surface
　　　C.prevent the sun's rays from reaching the earth's surface
　　　D.account for great changes in the climate in the northern hemiphere
　　69.Although the fuel consumption is greater in the northern hemisphere,temperatures there seem to be falling.This is _______.
　　　A.mainly because the levels of carbon dioxide are rising
　　　B.partly due to variations in the output of solar energy
　　　C.possibly because the ice caps in the poles are melting
　　　D.exclusively due to the effect of the inertia of the earth's climate
　　70.On the basis of their models,scientists are of the opinion that ________.
　　　A.the climate of the world should be becoming cooler
　　　B.the new Ice Age will be delayed by the greenhouse effect
　　　C.the man - made warming effect helps to increase the solar effects
　　　D.it will take thousands of years for the inertia of the earth's climate to take effect

D

　　In the atmosphere,carbon dioxide actd rather like a one-way mirror or the glass in the roof of a greenhouse which allows the sun's rays to enter but prevents the heat from excaping.

　　According to a weather expert's prediction,the atmosphere will be 3 warmer in the year 2050 than it is today, if man continues to burn luels at the present rate. If this warming up took place,the ice caps in the poles would begin to melt,thus raising sea level several meters and severely flooding coastal cities.Also，the increase in atmospheric temperature would lead to great changes in the climate of the northern hemisphere(半球),psooicbly resulting in an alteration of earth's chief food growing zones.

　　In the past,concern about a man - made warming of the earth has concentrated on the Arctic because the Antarctic is much colder and has a much thicker ice sheet.But the weather experts are now paying more attention to West Antarctic,which may be affected by a warming on the scale that will possibly take place in the next fifty years from on burning of fuels.

　　Satellite pictures showthat large areas of Antarctic ice are already disappearing.The evidence available suggests that a warming has taken place.This fits the theory that carbon dioxide warms the earth.

　　However,most of the fuel is burnt in the northern hemisphere,where temperatures seem to be falling.Scientists conclude,therefore,that up to now natural influences on the weather have exceeded those caused by man.The question is:Which natural cause has most effect on the weather?

　　One possibility is the variable behavior of the sun.Astronomers at one research station have studied the hot spots and cold spots(that is,the relatively less hot spots) on the sun. As the sun rotates(旋转),every 27.5 days,it presents hotter or colder faces to the earth,and different aspects to different parts of the earth.This seems to have a considerable effect on the distribution of the earth's atmospheric pressure,and consequently on wind circulation.The sun is also variable over a long term:its heat output goes up and down in cycles,the latest trend being downward.

　　Scientists are now finding mutual relations between models of solar weather interactions and the actual climate over many thousands of years ,including the last Ice Age.The problem is that the models are predicting that the world should be entering a new Ice Age and it is not.

　　One way of solving this theoretical difficulty is to assume a delay of thousands of years while the solar effects overcome the inertia(不活动，惰性) of the earth's climate.If this is right,the warming effect of carbon dioxide might thus be serving as a useful counter balance to the sun's diminishing heat.

　　68.It can be concluded that a concentration of carbon dioxide in the atmosphere would ___.

　　　A.mean a warming - up im the Arctic

　　　B.raise the temperature of the earth's surface

　　　C.prevent the sun's rays from reaching the earth's surface

　　　D.account for great changes in the climate in the northern hemiphere

　　69.Although the fuel consumption is greater in the northern hemisphere,temperatures there seem to be falling.This is _______.

　　　A.mainly because the levels of carbon dioxide are rising

　　　B.partly due to variations in the output of solar energy

　　　C.possibly because the ice caps in the poles are melting

　　　D.exclusively due to the effect of the inertia of the earth's climate

　　70.On the basis of their models,scientists are of the opinion that ________.

　　　A.the climate of the world should be becoming cooler

　　　B.the new Ice Age will be delayed by the greenhouse effect

　　　C.the man - made warming effect helps to increase the solar effects

　　　D.it will take thousands of years for the inertia of the earth's climate to take effect

E
　　　Scholars and students have always been great travelers. The official case for “academic mobility” is now often stated in impressive terms as a fundamental necessity for economic and social progress in the world, and debated in the areas of Europe, but it is certainly nothing new. Serious students were always ready to go abroad in search of the best teachers and the most famous academies; in search of the purest philosophy, the most effective medicine, the likeliest road to gold
　　Mobility of this kind meant also mobility of ideas, their moving across borders, their simultaneous  (同时发生的)impact upon many groups of people. The point of learning is to share it, whether with students or with colleagues; one thinks that only eccentrics have no interest in being credited(相信) with a striking discovery, or a new technique. It must also have been comforting to know that other people in other parts of the world were about to make the same discovery or were thinking along the same lines, and that one was not quite alone, faced by question, ridicule or neglect.
　　In the twentieth century, and particularly in the last 20 years, the old footpaths of the wandering scholars have become vast highways. The vehicle which has made this possible has of course been the aeroplane, making contact between scholars even in the most distant places immediately available, and providing for the very rapid transmission of knowledge.
　　Apart from the vehicle itself, it is fairly easy to identify the main factors which have brought about the recent explosion in academic movement. Some of these are purely quantitative and require no further mention: there are far more centres of learning, and a far greater number of scholars and students.
　　In addition one must recognize the very considerable increase of all kinds of subjects, particularly in the sciences, which by widening the total area of advanced studies has produced an enormous number of specialists whose particular interests are precisely defined. These people would work in some isolation if they were not able to keep in touch with similar isolated groups in other countries.
71.It can be concluded from the passage that"academic mobility"_____.
A.means the friendship formed by scholars on the trip
B.is a program carried out by governments
C.has been put great emphasis on in the world
D.means going abroad in search of the best teachers
72.The word "eccentric" underlined in the second paragraph most probably means_____.
A.a rather strange person                              B.a person of no exceptional ability
C.an ambitious person                                  D.peculiar or unusual
73.In the eyes of the author,what happens to a scholar who shares his ideas with his      
colleagues?
A.He risks his ideas being stolen.                   B.He gains recognition for his achievement
C.He is considered as an eccentric.                 D.He is credited with a striking discovery.
74.According to the passage,the recent growth in air travel has meant that_____.
A.travel around the world becomes realistic and affordable
B.more students from remote areas can attend universities
C.all kinds of information can be shared by more people
D.scholars can meet each other more easily
75.The author thinks that it's important for scholars to be able to travel because_____.
A.their laboratories are in remote places
B.there is too much stress at universities
C.their fellow experts are spread across the world
D.there are so many people working in similar fields