『新东方在线托福阅读』为托福考生准备了ETS托福TPO/Official 3 Passage 2阅读练习：The word “unprecedented” in the passage is closest in meaning to真题题目及答案解析，TPO/Official 3 Passage 2阅读原文范文音频翻译

托福TPO/Official 3 Passage 2阅读原文The word “unprecedented” in the passage is closest in meaning to题目答案及解析-新东方托福官方网校手机版

十九世纪八十年代，一批农民和农场主来到了美国中部大平原的广袤草原定居。

The vast grasslands of the High Plains in the central United States were settled by farmers and ranchers in the 1880’s

该区域有半干旱的气候，人们定居于此五十年之后，这个区域一直维系着一种低强度的畜牧业和小麦种植经济。

This region has a semiarid climate, and for 50 years after its settlement, it supported a low-intensity agricultural economy of cattle ranching and wheat farming

然而，在二十世纪早期，大平原大部分地区被发现地下有一层巨大的蓄水层（一种含有大量地下水的岩层）

In the early twentieth century, however, it was discovered that much of the High Plains was underlain by a huge aquifer (a rock layer containing large quantities of groundwater)

由于这个地方曾居住着一个叫做Ogallala Sioux的印第安民族，这个蓄水层被命名为奥加拉拉蓄水层。

This aquifer was named the Ogallala aquifer after the Ogallala Sioux Indians, who once inhabited the region.

奥加拉拉蓄水层是一种砂岩结构，其从德克萨斯西北绵延到南达科他州多达583,000平方公里的土地上。

The Ogallala aquifer is a sandstone formation that underlies some 583,000 square kilometers of land extending from northwestern Texas to southern South Dakota

雨水和雪融水在过去的三万年当中一直在奥加拉拉积聚。

Water from rains and melting snows has been accumulating in the Ogallala for the past 30,000 years

估计表明，奥加拉拉蓄水层有足够的水来填满（美国五大湖之一的）休伦湖。但不幸的是，在当前半干旱的气候条件下，这个地区的水补给率仅有微小的0.5公分每年。

Estimates indicate that the aquifer contains enough water to fill Lake Huron, but unfortunately, under the semiarid climatic conditions that presently exist in the region, rates of addition to the aquifer are minimal, amounting to about half a centimeter a year.

二十世纪三十年代早期的干旱年份，第一批井钻进了奥加拉拉蓄水层。

The first wells were drilled into the Ogallala during the drought years of the early 1930’s

接下来灌溉农业的快速发展（尤其是二十世纪五十年代以来）改变了该地区的经济。

The ensuing rapid expansion of irrigation agriculture, especially from the 1950’s onward, transformed the economy of the region

超过十万口井在从奥加拉拉蓄水层抽水。

More than 100,000 wells now tap the Ogallala

现代的灌溉设备在其强力的灌溉能力（日均喷水量450万升）之下，让该地区成为一种庄稼的环形绿色岛屿景观。

Modern irrigation devices, each capable of spraying 4.5 million liters of water a day, have produced a landscape dominated by geometric patterns of circular green islands of crops

奥加拉拉的水满足了美国大平原地区棉花、高粱、小麦、玉米的灌溉需求。

Ogallala water has enabled the High Plains region to supply significant amounts of the cotton, sorghum, wheat, and corn grown in the United States

另外，40%的美国谷物饲养的肉牛在此培育。

In addition, 40 percent of American grain-fed beef cattle are fattened here.

大平原地区极少的自然水补给率（即几乎没有自然水来补充水源）和有限水资源之下的前所未有利用让该地区的水位线急速下降。

This unprecedented development of a finite groundwater resource with an almost negligible natural recharge rate—that is, virtually no natural water source to replenish the water supply—has caused water tables in the region to fall drastically

在20世纪30年代，水井打到15米就可以有大量的地下水涌出；现在，他们必须要钻探到45到60米甚至更深的位置。

In the 1930’s, wells encountered plentiful water at a depth of about 15 meters; currently, they must be dug to depths of 45 to 60 meters or more

在一些地区，水位线下降速度达到了每年1米，这使得该地区必须定期加深水井的深度，并且用更强力的水泵抽水。

In places, the water table is declining at a rate of a meter a year, necessitating the periodic deepening of wells and the use of ever-more-powerful pumps

据估计，在当前的水位下降速率之下，40年之内奥加拉拉蓄水层的大部分区域都会面临枯竭。

It is estimated that at current withdrawal rates, much of the aquifer will run dry within 40 years

这种情形在德克萨斯州最为严重，这里气候最为干旱，用水量最大，并且蓄水层含水量又最少。

The situation is most critical in Texas, where the climate is driest, the greatest amount of water is being pumped, and the aquifer contains the least water

根据预测，到2030年，德克萨斯州下面的奥加拉拉蓄水层剩余的水量所能灌溉的土地英亩数将只有1980年的35%到40%。

It is projected that the remaining Ogallala water will, by the year 2030, support only 35 to 40 percent of the irrigated acreage in Texas that it supported in 1980.

农民们对于奥加拉拉蓄水层不可避免的枯竭命运反应不一而足。

The reaction of farmers to the inevitable depletion of the Ogallala varies

许多人已经尝试通过降低灌溉频率或者种植需水量更少的庄稼来节约用水。

Many have been attempting to conserve water by irrigating less frequently or by switching to crops that require less water

然而，其他人则秉承今朝有酒今朝醉的原则，趁现在大量用水依然能赚钱，最好仍然保持原来的用水模式并且重点种植需水量大的棉花这类高价值作物。

Others, however, have adopted the philosophy that it is best to use the water while it is still economically profitable to do so and to concentrate on high-value crops such as cotton

在得知他们的许多邻居在靠大量用水赚钱同时让整个区域的供水减少之后，那些想要节约用水的农民的积极性就减弱了。

The incentive of the farmers who wish to conserve water is reduced by their knowledge that many of their neighbors are profiting by using great amounts of water, and in the process are drawing down the entire region’s water supplies

面对日益严重的水危机，很多宏伟的调水工程投入运行，这些工程把密西西比河、密苏里河或阿肯色河的水通过运河或管道运输到了奥加拉拉地区。

In the face of the upcoming water supply crisis, a number of grandiose schemes have been developed to transport vast quantities of water by canal or pipeline from the Mississippi, the Missouri, or the Arkansas rivers

不幸的是，上述工程带来的是，该地区的用水成本增加了至少十倍，导致该地区的灌溉作物在国内和国际市场上在成本上没有竞争力。

Unfortunately, the cost of water obtained through any of these schemes would increase pumping costs at least tenfold, making the cost of irrigated agricultural products from the region uncompetitive on the national and international markets

最近有一些更有前景的实验，人们通过向地面注入压缩空气来释放地下水位上方的毛细水（土壤中的水）。

Somewhat more promising have been recent experiments for releasing capillary water (water in the soil) above the water table by injecting compressed air into the ground

然而，即使这种工艺过程是成功的，也会让用水成本提高到接近三倍。

Even if this process proves successful, however, it would almost triple water costs

随着新品种抗旱作物的不断开发，基因工程也可能会提供部分解决方案。

Genetic engineering also may provide a partial solution, as new strains of drought-resistant crops continue to be developed

无论对水危机的最终答案是什么，很明显的是在高原地区，灌溉水将永远不再是20世纪中叶农业繁荣时期的丰富，廉价的资源了。

Whatever the final answer to the water crisis may be, it is evident that within the High Plains, irrigation water will never again be the abundant, inexpensive resource it was during the agricultural boom years of the mid-twentieth century.

According to paragraph 1, which of the following statements about the High Plains is true?

According to paragraph 2, all of the following statements about the Ogallala aquifer are true EXCEPT:

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.

The word “ensuing” in the passage is closest in meaning to

In paragraph 3, why does the author provide the information that 40 percent of American cattle are fattened in the High Plains?

The word “unprecedented” in the passage is closest in meaning to

The word “virtually” in the passage is closest in meaning to

According to paragraph 4, all of the following are consequences of the heavy use of the Ogallala aquifer for irrigation EXCEPT:

According to paragraph 4, compared with all other states that use Ogallala water for irrigation, Texas

The word “inevitable” in the passage is closest in meaning to

Paragraph 5 mentions which of the following as a source of difficulty for some farmers who try to conserve water?

According to paragraph 6, what is the main disadvantage of the proposed plans to transport river water to the High Plains?

Look at the four squares  that indicate where the following sentence could be added to the passage. But even if uncooperative farmers were to join in the conservation efforts, this would only delay the depletion of the aquifer.  Where would the sentence best fit? Click on a square  to add the sentence to the passage.

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 sentences 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.

Depletion of the Ogallala Aquifer The vast grasslands of the High Plains in the central United States were settled by farmers and ranchers in the 1880’s. This region has a semiarid climate, and for 50 years after its settlement, it supported a low-intensity agricultural economy of cattle ranching and wheat farming. In the early twentieth century, however, it was discovered that much of the High Plains was underlain by a huge aquifer (a rock layer containing large quantities of groundwater). This aquifer was named the Ogallala aquifer after the Ogallala Sioux Indians, who once inhabited the region. The Ogallala aquifer is a sandstone formation that underlies some 583,000 square kilometers of land extending from northwestern Texas to southern South Dakota. Water from rains and melting snows has been accumulating in the Ogallala for the past 30,000 years. Estimates indicate that the aquifer contains enough water to fill Lake Huron, but unfortunately, under the semiarid climatic conditions that presently exist in the region, rates of addition to the aquifer are minimal, amounting to about half a centimeter a year. The first wells were drilled into the Ogallala during the drought years of the early 1930’s. The ensuing rapid expansion of irrigation agriculture, especially from the 1950’s onward, transformed the economy of the region. More than 100,000 wells now tap the Ogallala. Modern irrigation devices, each capable of spraying 4.5 million liters of water a day, have produced a landscape dominated by geometric patterns of circular green islands of crops. Ogallala water has enabled the High Plains region to supply significant amounts of the cotton, sorghum, wheat, and corn grown in the United States. In addition, 40 percent of American grain-fed beef cattle are fattened here. This unprecedented development of a finite groundwater resource with an almost negligible natural recharge rate—that is, virtually no natural water source to replenish the water supply—has caused water tables in the region to fall drastically. In the 1930’s, wells encountered plentiful water at a depth of about 15 meters; currently, they must be dug to depths of 45 to 60 meters or more. In places, the water table is declining at a rate of a meter a year, necessitating the periodic deepening of wells and the use of ever-more-powerful pumps. It is estimated that at current withdrawal rates, much of the aquifer will run dry within 40 years. The situation is most critical in Texas, where the climate is driest, the greatest amount of water is being pumped, and the aquifer contains the least water. It is projected that the remaining Ogallala water will, by the year 2030, support only 35 to 40 percent of the irrigated acreage in Texas that it supported in 1980. The reaction of farmers to the inevitable depletion of the Ogallala varies. Many have been attempting to conserve water by irrigating less frequently or by switching to crops that require less water.  Others, however, have adopted the philosophy that it is best to use the water while it is still economically profitable to do so and to concentrate on high-value crops such as cotton.  The incentive of the farmers who wish to conserve water is reduced by their knowledge that many of their neighbors are profiting by using great amounts of water, and in the process are drawing down the entire region’s water supplies.  In the face of the upcoming water supply crisis, a number of grandiose schemes have been developed to transport vast quantities of water by canal or pipeline from the Mississippi, the Missouri, or the Arkansas rivers.  Unfortunately, the cost of water obtained through any of these schemes would increase pumping costs at least tenfold, making the cost of irrigated agricultural products from the region uncompetitive on the national and international markets. Somewhat more promising have been recent experiments for releasing capillary water (water in the soil) above the water table by injecting compressed air into the ground. Even if this process proves successful, however, it would almost triple water costs. Genetic engineering also may provide a partial solution, as new strains of drought-resistant crops continue to be developed. Whatever the final answer to the water crisis may be, it is evident that within the High Plains, irrigation water will never again be the abundant, inexpensive resource it was during the agricultural boom years of the mid-twentieth century.