同学们在备考tpo43阅读答案+原文+解析【El
Nirio】。
El Nirio
The cold Humboldt Current of the Pacific Ocean flows toward the equator along the coasts of Ecuador and Peru in South America. When the current approaches the equator, the westward-flowing trade winds cause nutrient-rich cold water along the coast to rise from deeper depths to more shallow ones. This upwelling of water has economic repercussions. Fishing, especially for anchovies, is a major local industry.
Every year during the months of December and January, a weak, warm countercurrent replaces the normally cold coastal waters. Without the upwelling of nutrients from below to feed the fish, fishing comes to a standstill. Fishers in this region have known the phenomenon for hundreds of years. In fact, this is the time of year they traditionally set aside to tend to their equipment and await the return of cold water. The residents of the region have given this phenomenon the name of El Nifio，,which is Spanish for "the child," because it occurs at about the time of the celebration of birth of the Christ child.
While the warm-water countercurrent usually lasts for two months or less, there are occasions when the disruption to the normal flow lasts for many months. In these situations, water temperatures are raised not just along the coast, but for thousands of kilometers offshore. Over the last few decades, the term El Nifio has come to be used to describe these exceptionally strong episodes and not the annual event. During the past 60 years, at least ten El Nifios have been observed Not only do El Niftos affect the temperature of the equatorial Pacific, but the strongest of them impact global weather.
The processes that interact to produce an El Nifio involve conditions all across the Pacific, not just in the waters off South America. Over 60 years ago, Sir Gilbert Walker, a British scientist, discovered a connection between surface pressure readings at weather stations on the eastern and western sides of the Pacific. He noted that a rise in atmospheric pressure in the eastern Pacific is usually accompanied by a fall in pressure in the western Pacific and vice versa. He called this seesaw pattern the Southern Oscillation. It was later realized that there is a close link between El Nino and the Southern Oscillation. In fact, the link between the two is so great that they are often referred to jointly as ENSO (El Nino-Southern Oscillation).
During a typical year, the eastern Pacific has a higher pressure than the western Pacific does. This east-to-west pressure gradient enhances the trade winds over the equatorial waters. This results in a warm surface current that moves east to west at the equator. The western Pacific develops a thick, warm layer of water while the eastern Pacific has the cold Humboldt Current enhanced by upwelling. However, in other years the Southern Oscillation, for unknown reasons, swings in the opposite direction, dramatically changing the usual conditions described above, with pressure increasing in the western. Pacific and decreasing in the eastern Pacific. This change in the pressure gradient causes the trade winds to weaken or, in some cases, to reverse. This then causes the warm water in the western Pacific to flow eastward, increasing sea-surface temperatures in the central and eastern Pacific. The eastward shift signals the beginning of an El Nifio.
Scientists try to document as many past El Nino events as possible by piecing together bits of historical evidence, such as sea-surface temperature records, daily observations of atmospheric pressure and rainfall, fisheries’ records from South America, and the writings of Spanish colonists dating back to the fifteenth century. From such historical evidence we know that El Nirtos have occurred as far back as records go. It would seem that they are becoming more frequent. Records indicate that during the sixteenth century, an El Nino occurred on average every six years. Evidence gathered over the past few decades indicates that El Ninos are now occurring on average a little over every two years. Even more alarming is the fact that they appear to be getting stronger. The 1997-1998 El Nifio brought copious and damaging rainfall to the southern United States, from California to Florida. Snowstorms in the northeast portion of the United States were more frequent and intense than in most years.
本文是托福tpo43阅读答案+原文+解析【El Nirio】。
1. The word "approaches" in the passage is closest in meaning to【词汇题】
A nears
B crosses
C travels along
D leaves
答案： A
解析：approach接近，靠近，对应选项A，靠近。
2. According to paragraph 1, what happens when the Humboldt Current interacts with westward flowing trade winds? 【事实信息题】
A Anchovies from southern waters are carried northward.
B Cold water from lower depths is brought closer to the surface.
C The Humboldt Current stops flowing toward the equator.
D The Humboldt Current begins to flow closer to the coasts of Ecuador and Peru.
答案： B
解析：定位句When the current approaches the equator, the westward-flowing trade winds cause nutrient-rich cold water along the coast to rise from deeper depths to more shallow ones. 当气流接近赤道,向西吹动的信风导致富含营养的冷水沿着海岸上升，从更深的深度变为浅的。因此正确答案为B。
3.Which of the following questions about the El Nino phenomenon is NOT answered in paragraph 2 ? 【否定事实信息题】
A Why is the El Niflo phenomenon called El Nirto?
B How do fishers spend their time during the El Nifio season?
C How do coastal fish obtain enough nutrients during the El Nifio season?
D Is the temperature of coastal waters different during the El Niflo season than it is the rest of the year?
答案： C
解析：A选项对应第二段最后一句，B选项对应第四句，D选项对应第一句，因此正确答案为C。
4. The word "exceptionally"，in the passage is closest in meaning to【词汇题】
A obviously
B unusually
C relatively
D occasionally
答案： B
解析：exceptionally异常地;特殊地;例外地，对应选项B，不寻常地。
5. Paragraph 3 supports which of the following statements about El Ninos, as that term is now used? 【事实信息题】
A El Nifios can originate in areas other than the Pacific Ocean.
B El Nifios can arise when warm currents last for two months or less.
C El Nifios affect water temperatures long distances from the South American coast.
D Multiple El Niflos can arise within a single calendar year.
答案： A
解析：B选项的can arise错误， C的from the South American coast 错误，D的can arise within a single calendar year错误。因此正确答案为A。
6. The phrase "is usually accompanied by” in the passage is closest in meaning to【词汇题】
A usually develops before
B usually occurs together with
C is usually indicated by
D is usually caused by
答案： B
解析：is usually accompanied by是通常伴随着…，对应选项B通常与…发生在一起。
7. The word "jointly" in the passage is closest in meaning to【词汇题】
A together
B therefore
C rightfully
D simply
答案： A
解析：jointly共同地;连带地，对应选项A，一起，同时。
8. According to paragraph 4, what did Sir Gilbert Walker discover? 【事实信息题】
A There is a close link between El Nifio and the Southern Oscillation.
B Surface pressure readings all across the Pacific first rise and then fall before an El Nifio occurs.
C Surface pressure on one side of the Pacific tends to fall when pressure rises on the opposite side.
D The formation of an El Nirto depends on conditions all across the Pacific, not just in the waters off of South America.
答案： C
解析：定位句Over 60 years ago, Sir Gilbert Walker, a British scientist, discovered a connection between surface pressure readings at weather stations on the eastern and western sides of the Pacific. 在60年前, 英国科学家吉尔伯特沃克爵士,发现了一个在东部气象站和西部的太平洋表面压力读数之间的关系。下文提到他将此关系成为Southern Oscillation，对应选项C。
9. According to paragraph 5, what is the end result of the east-to-west pressure gradient in the eastern Pacific during a typical year? 【事实信息题】
A The formation of a thick, warm layer of water in the western Pacific
B The reversal of the pressure gradient to west-to-east by the end of the year
C A change in the direction of the Southern Oscillation
D The eastward flow of warm water from the western Pacific
答案： A
解析：定位句The western Pacific develops a thick, warm layer of water while the eastern Pacific has the cold Humboldt Current enhanced by upwelling. 西太平洋形成了厚且温暖的水层，而东太平洋的上升流使洪堡寒流增强。因此正确答案为A。
10. According to paragraph 5, all of the following changes occur in the Pacific before an El Nifio begins EXCEPT: 【否定事实信息题】
A Pressure increases in the western Pacific and decreases in the eastern Pacific.
B The trade winds decrease in intensity or reverse in the direction.
C Surface temperatures increase in the central and eastern Pacific.
D Ocean currents speed up as they move eastward.
答案： D
解析：A对应原文中的…with pressure increasing in the western. Pacific and decreasing in the eastern Pacific. B对应…in some cases, to reverse. C对应最后一句的increasing sea-surface temperatures in the central and eastern Pacific。因此正确答案为D。
11. What can be inferred about El Ninos from the historical evidence mentioned in paragraph 6 ? 【推断题】
A They have often brought damaging weather to parts of the United States.
B They have been occurring since at least the fifteenth century.
C They occurred less frequently in the sixteenth century than in the fifteenth.
D They have had stronger weather effects on the United States in recent decades than on other locations.
答案： B
解析：定位至第六段第一句此处无关键信息，因此用排除法，A选项的often brought damaging weather … of the United States无法推出，C的less frequently …than in the fifteenth无法推出，D的stronger weather effects…than on other locations无法推出。B选项的at least the fifteenth century对应原文的dating back to the fifteenth century，因此正确答案为B。
12. Why does the author include the information that in 1997-1998 "Snowstorms in the northeast portion of the United States were more frequent and intense than in most years"?【修辞目的题】
A To provide evidence supporting the claim that El Nifios are getting stronger
B To explain why the southern United States experienced copious and damaging rainfall in 1997-1998
C To show that traditional methods are not adequate for documenting the effects of El Niftos
D To identify a consequence of the fact that El Niflos are now occurring a little over once every two years
答案： A
解析：定位句The 1997-1998 El Nifio brought copious and damaging rainfall to the southern United States, from California to Florida. 1997 - 1998年的厄尔尼诺给美国南部带来了大量且破坏性的降雨，从加利福尼亚到佛罗里达。B的原因并没有进行解释，错误;C的not adequate for documenting 未提及，D的 identify a consequence未提及。因此正确答案为A。
13. Look at the four squares [■] that indicate where the following sentence could be added to the passage. 【句子插入题】
There is clear support for this view in the available documents.
Where would the sentence best fit? Click on a square [■] to add the sentence to the passage.
答案： B
解析：句中的support和available documents在原文中B处出现，对应Records，A处It为指代前文内容，不得断开，D处Even more与前文C处联系紧密，因此正确答案为B。
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 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. 【概要小结题】
Drag your answer choices to the spaces where they belong To remove an answer choice, click on it.
To review the passage, click VIEW TEXT
As it is currently used, the term El Nirio refers to a strong and lengthy disruption to the normal pattern of ocean currents, water temperatures, and winds in the Pacific.
Answer Choices
An El Nino typically begins when the Humboldt Current causes upwelling as it travels toward the equator along the coast of Peru and Ecuador.
El Nirlos are preceded by the reversal of the usual east-to- west pressure gradient in the Pacific, the weakening or reversal of the trade winds, and the movement of warm water eastward.
Comparisons of historical records with recent past events show that El Ninos are becoming more frequent and stronger.
In an El Nino, warm surface currents replace the Humboldt Current for many months, raising ocean temperatures far from the coast.
Scientists discovered the Southern Oscillation by taking surface-pressure readings at weather stations on both sides of the Pacific.
In recent decades, El Nifios have begun to occur north of the equator and thereby affect weather conditions in the United States.
答案： ACE
解析：A对应原文第一段主要内容概括，C对应第六段的事例及总结，E对应第四段的事例内容。
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