reading 2002-10-48

Question 40-50

Scientists have discovered that for the last 160,000 years, at least, there has  

been a consistent relationship between the amount of carbon dioxide in the air and  

the average temperature of the planet. The importance of carbon dioxide in  

regulating the Earth's temperature was confirmed by scientists working in eastern  

(5) Antarctica. Drilling down into a glacier, they extracted a mile-long cylinder of ice  

from the hole. The glacier had formed as layer upon layer of snow accumulated year  

after year. Thus drilling into the ice was tantamount to drilling back through time.

The deepest sections of the core are composed of water that fell as snow  

160,000 years ago. Scientists in Grenoble, France, fractured portions of the core and

(10)measured the composition of ancient air released from bubbles in the ice.  

Instruments were used to measure the ratio of certain isotopes in the frozen water to  

get an idea of the prevailing atmospheric temperature at the time when that  

particular bit of water became locked in the glacier.

The result is a remarkable unbroken record of temperature and of atmospheric

(15)levels of carbon dioxide. Almost every time the chill of an ice age descended on the  

planet, carbon dioxide levels dropped. When the global temperature dropped 9°F (5 °C),

carbon dioxide levels dropped to 190 parts per million or so. Generally, as each  

ice age ended and the Earth basked in a warm interglacial period, carbon dioxide  

levels were around 280 parts per million. Through the 160,000 years of that ice

(20)record, the level of carbon dioxide in the atmosphere fluctuated between 190 and  

280 parts per million, but never rose much higher-until the Industrial Revolution  

beginning in the eighteenth century and continuing today.

There is indirect evidence that the link between carbon dioxide levels and  

global temperature change goes back much further than the glacial record. Carbon

(25) dioxide levels may have been much greater than the current concentration during the

    Carboniferous period, 360 to 285 million years ago. The period was named for a

profusion of plant life whose buried remains produced a large fraction of the coal  

deposits that are being brought to the surface and burned today.

48.  The passage implies that the warmest temperatures among the periods mentioned occurred

(A)  in the early eighteenth century

(B)  160,000 years ago

(C)  at the end of each ice age

(D)  between 360 and 285 million years ago

50. The passage explains the origin of which of the following terms?  

(A)  Glacier (line5)

(B)  Isotopes (line 11)

(C)  Industrial Revolution (line 21)

(D)  Carboniferous period (lines 26

Answer: 48: A 我選D

             50: C 我選D

280 parts per million, but never rose much higher-until the Industrial Revolution   

beginning in the eighteenth century and continuing today. 看出，应该选A，

50选C 偶也赞同，主要是到文章中查找有没有细节描述。。