tpo3.docx

1、tpo3智课网TOEFL备考资料tpo3阅读文本答案解析+翻译 摘要： 下面是小马过河整理的托福tpo3阅读文本答案解析+翻译，同学们可在线免费下载托福TPO全套试题word或者PDF格式，希望对大家备考托福阅读考试有所帮助。 托福 TPO3阅读文本答案解析+翻译:Depletion of the Ogallala Aquifer 托福tpo3阅读原文 The vast grasslandsof the High Plains in the central United States were settled by farmers andranchers in the 1880s. This

2、region has a semiarid climate, and for 50 yearsafter its settlement, it supported a low-intensity agricultural economy ofcattle ranching and wheat farming. In the early twentieth century, however, itwas discovered that much of the High Plains was underlain by a huge aquifer (arock layer containing l

3、arge quantities of groundwater). This aquifer was namedthe Ogallala aquifer after the Ogallala Sioux Indians, who once inhabited theregion. The Ogallalaaquifer is a sandstone formation that underlies some 583,000 square kilometersof land extending from northwestern Texas to southern South Dakota. Wa

4、ter fromrains and melting snows has been accumulating in the Ogallala for the past30,000 years.Estimates indicate that the aquifer contains enough water tofill Lake Huron, but unfortunately, under the semiarid climatic conditions thatpresently exist in the region, rates of addition to the aquifer ar

5、e minimal,amounting to about half a centimeter a year. The first wellswere drilled into the Ogallala during the drought years of the early 1930s. Theensuingrapid expansion of irrigation agriculture, especially from the1950s onward, transformed the economy of the region. More than 100,000 wellsnow ta

6、p the Ogallala. Modern irrigation devices, each capable of spraying 4.5million liters of water a day, have produced a landscape dominated by geometricpatterns of circular green islands of crops. Ogallala water has enabled theHigh Plains region to supply significant amounts of the cotton, sorghum, wh

7、eat,and corn grown in the United States. In addition, 40 percent of Americangrain-fed beef cattle are fattened here. This unprecedented development of a finite groundwater resource with an almost negligible naturalrecharge ratethat is,virtually no natural water source to replenish the water supplyha

8、scaused water tables in the region to fall drastically. In the 1930s, wellsencountered plentiful water at a depth of about 15 meters; currently, they mustbe dug to depths of 45 to 60 meters or more. In places, the water table isdeclining at a rate of a meter a year, necessitating the periodic deepen

9、ing ofwells and the use of ever-more-powerful pumps. It is estimated that at currentwithdrawal rates, much of the aquifer will run dry within 40 years. Thesituation is most critical in Texas, where the climate is driest, the greatestamount of water is being pumped, and the aquifer contains the least

10、 water. Itis projected that the remaining Ogallala water will, by the year 2030, supportonly 35 to 40 percent of the irrigated acreage in Texas that is supported in1980. The reaction offarmers to the inevitabledepletion of the Ogallala varies. Many havebeen attempting to conserve water by irrigating

11、 less frequently or by switchingto crops that require less water. Others, however, have adopted the philosophythat it is best to use the water while it is still economically profitable todo so and to concentrate on high-value crops such as cotton. The incentive ofthe farmers who wish to conserve wat

12、er is reduced by their knowledge that manyof their neighbors are profiting by using great amounts of water, and in theprocess are drawing down the entire regions water supplies. In the face of theupcoming water supply crisis, a number of grandiose schemes have been developedto transport vast quantit

13、ies of water by canal or pipeline from theMississippi, the Missouri, or the Arkansas rivers. Unfortunately, the cost ofwater obtained through any of these schemes would increase pumping costs atleast tenfold, making the cost of irrigated agricultural products from theregion uncompetitive on the nati

14、onal and international markets. Somewhat morepromising have been recent experiments for releasing capillary water (water inthe soil) above the water table by injecting compressed air into the ground.Even if this process proves successful, however, it would almost triple watercosts. Genetic engineeri

15、ng also may provide a partial solution, as new strainsof drought-resistant crops continue to be developed. Whatever the final answerto the water crisis may be, it is evident that within the High Plains,irrigation water will never again be the abundant, inexpensive resource it wasduring the agricultu

16、ral boom years of the mid-twentieth century. 托福tpo3阅读试题 1. According toparagraph 1, which of the following statements about the High Plains is true? A.Until farmers andranchers settled there in the 1880s, the High Plains had never been inhabited. B.The climate ofthe High Plains is characterized by h

17、igher-than-average temperatures. C.The large aquiferthat lies underneath the High Plains was discovered by the Ogallala SiouxIndians. D.Before the early1900s there was only a small amount of farming and ranching in the High Plains. 2. According toparagraph 2, all of the following statements about th

18、e Ogallala aquifer aretrue EXCEPT: A.The aquiferstretches from South Dakota to Texas. B.The aquifers water comes from underground springs. C.Water has beengathering in the aquifer for 30,000 years. D.The aquifers water is stored in a layer ofsandstone. 3. Which of thesentences below best expresses t

19、he essential information in thehighlightedsentencein the passage (paragragh 2)? Incorrect choices change the meaningin important ways or leave out essential information. A.Despite thecurrent impressive size of the Ogallala aquifer, the regions climate keeps the rates of wateraddition very small. B.A

20、lthough theaquifer has been adding water at the rate of only half a centimeter a year, itwill eventually accumulate enough water of fill Lake Huron. C.Because of theregions present climaticconditions, water is being added each year to the aquifer. D.Even when theregion experiences unfortunate climat

21、ic conditions, the rates of addition ofwater continue to increase. 4. The word “ensuing”in the passage (paragraph 3) is closest inmeaning to A.continuing B.surprising C.initial D.subsequent 5. In paragraph 3,why does the author provide the information that 40 percent of American cattleare fattened i

22、n the High Plains? A.To suggest thatcrop cultivation is not the most important part of the economy of the HighPlains B.To indicate thatnot all economic activity in the High Plains is dependent on irrigation C.To provideanother example of how water from the Ogallala has transformed the economy ofthe

23、High Plains D.To contrastcattle-fattening practices in the High Plains with those used in other regionof the United States 6. The word “unprecedented”in the passage (paragraph 4) is closest in meaning to A.difficult tocontrol B.without anyrestriction C.unlike anythingin the past D.rapidly expanding

24、7. The word “virtually”in the passage (paragraph 4) is closest in meaning to A.clearly B.perhaps C.frequently D.almost 8. According toparagraph 4, all of following are consequences of the heavy use of the Ogallalaaquifer for irrigation EXCEPT: A.The recharge rateof the aquifer is decreasing. B.Water

25、 tables inthe region are becoming increasingly lower. C.Wells now have tobe dug to much greater depths than before. D.Increasinglypowerful pumps are needed to draw water from the aquifer. 9. According toparagraph 4, compared with all other states that use Ogallala waterforirrigation, Texas A.has the

26、 greatestamount of farmland being irrigated with Ogallala water B.contains thelargest amount of Ogallala water underneath the soil C.is expected toface the worst water supply crisis as the Ogallala runs dry D.uses the leastamount of Ogallala water for its irrigation needs 10. The word “inevitable”in

27、 the passage (paragraph 5) is closest in meaning to A.unfortunate B.predictable C.unavoidable D.final 11. Paragraph 5 mentionswhich of the following as a source of difficulty for some farmers who try toconserve water? A.Crops that do notneed much water are difficult to grow in the High Plains. B.Far

28、mers who growcrops that need a lot of water make higher profits. C.Irrigating lessfrequently often leads to crop failure. D.Few farmers areconvinced that the aquifer will eventually run dry. 12. According toparagraph 6, what is the main disadvantage of the proposed plans to transportriver water to t

29、he High Plains? A.The rivers cannotsupply sufficient water for the farmers needs. B.Increasedirrigation costs would make the products too expensive. C.The costs ofusing capillary water for irrigation will increase. D.Farmers will beforced to switch to genetically engineered crops. 13. Look at thefou

30、r squares that indicate wherethe following sentence could be added to the passage.But even ifuncooperative farmers were to join in the conservation efforts, this would onlydelay the depletion of the aquifer. The reaction offarmers to the inevitable depletion of the Ogallala varies. Many have beenatt

31、empting to conserve water by irrigating less frequently or by switching tocrops that require less water. Others, however, have adopted the philosophy that it is best to usethe water while it is still economically profitable to do so and to concentrateon high-value crops such as cotton.The incentive

32、ofthe farmers who wish to conserve water is reduced by their knowledge that manyof their neighbors are profiting by using great amounts of water, and in theprocess are drawing down the entire regions watersupplies. In the face of theupcoming water supply crisis, a number of grandiose schemes have been developedto tr