2004年1月份托福阅读真题及其答案

 

Questions 41-50
          The atmosphere that originally surrounded Earth was probably much different from
     the air we breathe today. Earths first atmosphere (some 4.6 billion years ago) was most
     likely hy~ogen and helium--.the two most abundant gasses found in the universe--as
     Line well as hydrogen compounds, such as methane and ammonia, Most scientists feel that
     5 this early atmosphere escaped into space from the Earths hot surface.
          A second, more dense atmosphere, however, gradually enveloped Earth as gasses
     from molten rocks within its hot interior escaped through volcanoes and steam vents.
     We assume that volcanoes spewed out the same gasses then as they do today: mostly
     water vapor (about g0 percent), carbon dioxide (about ten percent), and up to a few
     10 percent nitrogen. These same gasses probably created Earths second atmosphere.
         As millions of years passed, the constant outpouring of gasses from the hot
     interior--known as outgassing--provided a rich supply of water vapor, which formed
     into clouds. Rain fell upon Earth for many thousands or years, forming the rivers,
     lakes, and oceans of the world. During this Lime, large amounts of carbon dioxide were
       15 dissolved in the oceans. Through chemical and biological processes, much of the carbon
     dioxide became locked up in carbon sedimentary rocks, such as limestone. With much
     of the water vapor already condensed into water and the concentration of carbon dioxide
     dwindling, the atmosphere gradually became rich nitrogen.
         It appears that oxygen, the second most abundant gas in todays atmosphere, probably
     20 began an extremely slow increase in concentration as energetic rays from the sun split
     water vapor into hydrogen and oxygen during a process called photodissociation. The
     hydrogen, being lighter, probably rose and escaped into space, while the oxygen remained
     in the atmosphere.
         This slow increase in oxygen may have provided enough of this gas for primitive
     25 plants to evolve, perhaps two to three billion years ago. Or the plants may have evolved
     in an almost oxygen-free (anaerobic) environment. At any rate, plant growth greatly
     enriched our atmosphere with oxygen. The reason for this enrichment is that plants, in
     the presence of sunlight, process carbon dioxide and water to produce oxygen.

7. By the end of the eighteenth century, the publishers of children’s looks in the United States were most concerned about which of the following? 

 A) Attracting children with entertaining stories that provided lessons of correct behavior    

 B) Publishing literature consisting of exciting stories that would appeal to both children and adults    

 C) Expanding markets for books in both Britain and the United States    

 D) Reprinting fictional books from earlier in the century   

 
41. What is the main idea of the passage? 

 A) The original atmosphere on Earth was unstable.    

 B) The atmosphere on Earth has changed over time.    

 C) Hot underground gasses created clouds, which formed the Earth's atmosphere.    

 D) Plant growth depended on oxygen in the Earth's atmosphere.   

 
42. The word "enveloped" in line 6 is closest in meaning to 

 A) surrounded    

 B) changed    

 C) escaped    

 D) characterized   

 
43. The word "they' in line 8 refers to 

 A) gasses    

 B) volcanoes    

 C) steam vents    

 D) rocks   

 
44. According to the passage, outgassing eventually led to all of the following EXCEPT 

 A) increases in the carbon dioxide content of sedimentary rocks    

 B) the formation of bodies of water    

 C) decreases in the level of nitrogen    

 D) the formation of clouds   

 
45. The word "gradually" in line 18 is closest in meaning to 

 A) accidentally    

 B) quickly    

 C) in the end    

 D) by degrees   

 
46. The passage suggests that oxygen remained in the atmosphere because 

 A) it was caused by outgassing    

 B) it was heavier than hydrogen    

 C) hydrogen became trapped in limestone    

 D) rays from the sun created equal amounts of hydrogen and oxygen   

 
47. The author uses the word "Or" in line 25 to
     

 A) criticize the previous suggestion   

 B) provide unrelated information   

 C) propose a similar idea   

 D) suggest an alternative   

 
48. The phase “At any rate ”in line 26 is closest in meaning to 

 A) regardless    

 B) in addition    

 C) although unlikely    

 D) fortunately   

 
49. The author organizes the discussion of the Earth's atmosphere in terms of the 

 A) role of volcanoes in its formation    

 B) occur in which changes occurred    

 C) time it took for the Earth's surface: to cool and nitrogen to appear    

 D) chemical and physical features of gasses   

 
50. Which of the following does the passage mention as necessary for both the production of oxygen by photodissociation and the production of oxygen by plants? 

 A) Water    

 B) Hydrogen    

 C) Carbon dioxide    

 D) Nitrogen    

0401 ：1-50答案
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