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[机经题库答案] 托福阅读农业类真题Water Management in Early Agriculture原文+题目汇总

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发表于 2017-5-5 15:01 |显示全部楼层
类别:农业类
真题140412CN-P2
Title:Water Management in Early Agriculture
As the first cities  formed in Mesopotamia in the Middle  East, probably around  3000 B.C., it became necessarily to provide  food for larger populations, and thus to find ways of increasing agricultural production. This, in turn, led to the  problem of obtaining sufficient water.
  
  
Irrigation must have started on a small  scale with rather  simple constructions, but  as its value became apparent, more effort was invested in new construction to divert more water into the  canals and to extend the canal system to reach greater  areas of potential farmland. Because of changing water  levels and clogging by waterborne particles, canals and their  intakes required additional labor to maintain, besides the  normal labor required to guide water from field to field. Beyond this,some personnel had to be devoted to making decisions about the allocation of available water  among the users and ensuring that these directions were carried out. With irrigation water also came  potential problems, the most obvious being the susceptibility of low-lying farmlands to disastrous  flooding and the longer-term problem of salinization (elevated levels of salt in the soil).  To combat flooding from rivers, people from early historic times until  today have constructed protective levees  (raised barriers of earth) between  the river and the  settlement or fields to be protected. This, of course,  is effective up to a certain level  of flooding but changes the basic water patterns of the area and can multiply the damage when the flood  level exceeds the height of the levee.
  
  
Salinization is caused by an  accumulation of salt in the soil near its surface. This salt is carried by river water from the sedimentary rocks in the mountains and deposited on the Mesopotamian fields during natural  flooding or purposeful irrigation. Evaporation of water sitting on the surface in hot climates is rapid, concentrating the salts in the  remaining water that then descends  through the soil to the underlying water table. In southern Mesopotamia, for example, the natural water  table comes to within roughly  six feet of the surface. Conditions of excessive irrigation bring the water table  to eighteen inches,  and water can rise further  to the root zone, where the  high concentration of salts would  kill most plants.
  
  
Solutions  for salinization were not as straightforward as for flooding, but even in ancient times it was understood that the deleterious effects of salinization could be minimized by removing  harmful elements through  leaching the fields  with additional fresh water,  digging deep wells to  lower the water table, or instituting a system  of leaving fields uncultivated. The first two cures would have required considerable labor,  and the third  solution would have  led to diminished productivity, not often viewed  as a likely decision in periods of growing population. An effective irrigation system laid the foundation for many of the world’s early civilizations, but it also required a great deal of labor input.
  
  
Growing agrarian societies often  tried to meet their food-producing needs by  farming less-desirable hill  slopes surrounding the favored low-lying  valley bottoms. Since bringing irrigation water to a hill slope  is usually impractical, the key is effective utilization of rainfall. Rainfall either  soaks into the soil or runs off of it due to gravity. A soil that  is deep, well-structured, and covered by protective vegetation and much will normally absorb almost all of the rain that falls on it, provided that the slope  is not too steep. However, soils that have lost their vegetative cover and  surface mulch will absorb much less, with almost half the water being carried  away by runoff in more extreme conditions. This runoff carries with it topsoil  particles, nutrients, and humus (decayed vegetable matter) that are  concentrated in the topsoil. The loss of this material reduces the thickness  of the rooting zone and its capacity to absorb moisture for crop needs.
  
  
The most  direct solution to this problem  of slope runoff  was to lay lines of stones along  the contours of the slope and hence, perpendicular to the probable flow of water  and sediment. These stones  could then act as small dams, slowing the downhill flow of water and allowing more water  to infiltrate and soil particles to collect behind the dam. This provided a  buildup of sediments for plants  and improved the landscape’s water-retention properties.
  
  
Paragraph 2
  
Irrigation must have started on a small  scale with rather  simple constructions, but  as its value became apparent, more effort was invested in new construction to divert more water into the  canals and to extend the canal system to reach greater  areas of potential farmland. Because of changing water  levels and clogging by waterborne particles, canals and their  intakes required additional labor to maintain, besides the  normal labor required to guide water from field to field. Beyond this, some personnel had to be devoted to making  decisions about the allocation of available water among the users and  ensuring that these directions were carried out. With irrigation water also came potential  problems, the most obvious being the susceptibility of low-lying farmlands to disastrous  flooding and the longer-term problem of salinization (elevated levels of salt in the soil).  To combat flooding from rivers, people from early historic times until  today have constructed protective levees  (raised barriers of earth) between  the river and the  settlement or fields to be protected. This, of course,  is effective up to a certain level  of flooding but changes the basic water patterns of the area and can multiply the damage when the flood  level exceeds the height of the levee.
  
  
1.        All of the following are  mentioned in paragraph 2 as operations involved in the Mesopotamian irrigation system EXCEPT
  
¡ determining  how much irrigation water should be distributed to various farmers
  
¡ widening  existing canals so they could hold more water
  
¡ removing  undesirable materials from the intakes of irrigation canals
  
¡  building new canals so irrigation  water could be transported to distant areas Paragraph 2 is marked with an  arrow [→]
  
  
2.        According to paragraph 2, protective levees  can have which  of the following disadvantages?
  
¡ They  can greatly increase the destruction caused by floodwaters when floodwaters are higher  than the levee.
  
¡ They  can fail even when the flood level remains below the height of the levee.
  
¡ They  can lead over time to a serious salinization  problem.
  
¡  They can cause damaging floods to  occur more frequently by changing basic water patterns.
  
Paragraph 2 is marked with an arrow [→]
  
  
3.       Paragraph 2 suggests that  irrigation increased the likelihood of destructive floods  because
  
¡  irrigated fields were often in locations that  tended to flood naturally
  
¡  the canal intakes for irrigation water often  did not work
  
¡  most irrigation canals were too narrow and  thus overflowed
  
¡  levees built to protect irrigation  systems required maintenance
  
  
Paragraph  2 is marked with an arrow [→]
  
  
4.        The  word “potential” in the passage is  closet in meaning to
  
¡ serious
  
¡ basic
  
¡ new
  
¡ possible
  
  
Paragraph 3
  
Salinization is caused by an accumulation of salt in the soil near its  surface. This salt is carried by river water from the sedimentary rocks in the mountains and deposited on the Mesopotamian fields during natural  flooding or purposeful irrigation. Evaporation of water sitting on the surface  in hot climates is rapid, concentrating the salts in the remaining  water that then descends through the  soil to the underlying water table. In southern Mesopotamia, for example, the natural water  table comes to within roughly six feet of the surface. Conditions of excessive irrigation bring the water table  to eighteen inches,  and water can rise further  to the root zone, where the  high concentration of salts would  kill most plants.
  
  
5.        The  word “accumulation” in the passage is  closet in meaning to
  
¡ distribution
  
¡ mixture
  
¡ buildup
  
¡ exchange
  
  
6.        According to paragraph 3, excessive  irrigation can destroy crops by
  
¡ raising  salty water to the level of the roots
  
¡ forcing  the roots of plants to grow close to the surface
  
¡ taking  the place of some natural flooding
  
¡  creating salt deposits on the  surface of the soil
  
  
Paragraph  3 is marked with an arrow [→]
  
  
Paragraph 4
  
Solutions  for salinization were not as straightforward  as for flooding, but even  in ancient times it was understood that  the deleterious effects of salinization could  be minimized by removing  harmful elements through  leaching the fields  with additional fresh water,  digging deep wells to  lower the water table, or instituting a system  of leaving fields uncultivated. The first two cures would have required considerable labor,  and the third  solution would have  led to diminished productivity, not  often viewed as a likely decision in periods of growing population. An effective irrigation system laid  the foundation for many of the world’s early  civilizations, but it also required  a great deal of labor input.
  
  
7.       The word “straightforward”  in the passage is closet in meaning to
  
¡  successful
  
¡  simple
  
¡  common
  
¡  complex
  
  
8.        According to paragraph 4,  which of the following is true of the more-likely-used solutions to the problem of salinization?
  
¡ They  resulted in a decrease in the amount of food that was produced.
  
¡  They succeeded only on areas where the  natural water table was especially low.
  
¡  They often demanded much time and effort on the part of their users.
  
¡  They often led to other  technological advances.
  
  
Paragraph  4 is marked with an arrow [→]
  
  
Paragraph 5
  
Growing agrarian societies often  tried to meet their food-producing needs by  farming less-desirable hill  slopes surrounding the favored low-lying  valley bottoms. Since bringing irrigation water to a hill slope  is usually impractical, the key is effective utilization of rainfall. Rainfall either  soaks into the soil or runs off of it due to gravity. A soil that  is deep, well-structured, and covered by protective vegetation and much will normally absorb almost all of the rain that falls  on it, provided that the slope is not too steep. However, soils  that have lost their vegetative cover and  surface mulch will absorb much less, with almost half the water being carried  away by runoff in more extreme conditions. This runoff carries  with it topsoil  particles, nutrients, and humus (decayed vegetable matter)  that are concentrated in the topsoil. The loss of this material reduces the thickness of the rooting zone and its capacity to absorb moisture for crop needs.
  
  
9.        According to paragraph 5, which  of the following was the main challenge faced by early agricultural  societies that wanted to grow crops on hill  slopes?
  
¡ Getting  enough irrigation water to the hill slope
  
¡  Growing crops without disturbing the natural  vegetative cover
  
¡  Retaining rainwater and thus preventing  excessive runoff
  
¡  Identifying  crops that do not need a thick rooting zone
  
  
Paragraph 5 is marked with an arrow [→]
  
  
10.   Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.
  
¡ However, soils that are unable to  absorb much water experience massive runoff during heavy rains.
  
¡ However, where neither protective  vegetation nor mulch covers the soil, much rainwater can be lost to runoff.
  
¡ However, on extremely steep slopes there  is no vegetative cover or mulch to prevent runoff.
  
¡ However, in more extreme conditions  water that runs off can carry away the  vegetative cover and the surface mulch
  
  
11.    The  word “impractical” in the passage is  closet in meaning to
  
¡ unnecessary
  
¡ unsafe
  
¡ unrealistic
  
¡ unpredictable
  
  
Paragraph 6
  
The most  direct solution to this problem  of slope runoff  was to lay lines of stones along  the contours of the slope and hence, perpendicular to the probable flow of water  and sediment. These stones  could then act as small dams, slowing the downhill flow of water and allowing more water  to infiltrate and soil particles to collect behind the dam. This provided a  buildup of sediments for plants  and improved the  landscape’s water-retention properties.
  
  
12.    Which of the following best describes how  paragraph 6 relates to paragraph 5?
  
¡ Paragraph 6 describes how the solution to a problem identified in paragraph 5 created unexpected benefits.
  
¡ Paragraph  6 compares two possible solutions to a problem described in paragraph 5.
  
¡ Paragraph 6 explains how the attempt  to solve a problem introduced in paragraph 5 led to more difficult problems.
  
¡  Paragraph  6 explains one way in which a difficulty described in paragraph 5 was  resolved.
  
  
Paragraphs5 and 6 is marked with an arrow [→]
  
  
Paragraph 3
  
Salinization  is caused by an accumulation of salt in the soil near its surface. ■This salt  is carried by river water from the sedimentary rocks in the mountains and  deposited on the Mesopotamian  fields during natural flooding or purposeful irrigation. Evaporation of water  sitting on the surface in   hot  climates  is   rapid,  concentrating  the   salts  in  the   remaining  water  that   then descends through the  soil to the underlying water table.   ■In southern Mesopotamia, for example, the natural water table comes  to within roughly six feet of the surface. ■Conditions of excessive  irrigation bring the water table to eighteen inches, and water can rise  further to the root zone, where the high concentration of salts would kill  most plants.■
  
  
13.    Look at the four squares  [■] that indicate where the following sentence could be added to the  passage.
  Natural flooding, however, does not raise  the water table  nearly as much  and thus does not  have these sorts of consequences.  
  
Where  would the sentence best fit? Click  on a square [■] to add the sentence to the passage.
  
  
14.   Directions: An introductory sentence for a brief summary  of the passage is provided  below. Complete the summary  by selecting the THREE answer choices that express the most important  ideas in the passage. Some answer choices do not belong in the summary  because they express ideas that are not presented in the passage or are minor  ideas in the passage. This question is worth 2 points.
  
  
Drag your choices to the spaces  where they belong. To review  the passage, click  on View Text.
  
            
As  cities       emerged       and  populations       grew       in  Mesopotamia,       more  water  had       to  be  provided       to increase      agricultural      production.
      
      
      
      
      
  
  
     
  Answer Choices  
  
¡   Early on, irrigation was recognized as a valuable  practice, even though it was  labor-intensive and brought with it problems of salinization and damaging floods.
  
¡   Levees were the major means of protection against flooding, while leaching with added  water and lowering the water table helped to control salinization.
  
¡   Because of the enormous amount of labor involved in irrigating fields, farming was increasingly moved to hill slopes, where irrigation  systems required less labor.
  
¡   The mountain water that was used to irrigate farmland in  Mesopotamia was exceptionally high in salt, causing rapid  salinization of the soil.
  
¡   The practice of leaving fields uncultivated periodically  was used primarily by societies  lacking a large labor force.
  
¡   As cultivation was extended to hill slopes, methods were  developed to better retain water  from rainfall for crops growing on hillsides.
  
  

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