托福TPO47閱讀真題解析：Passage 1

TPO，即toefl Practice Online的首寫字母，就是托福在線練習的意思，TPO可以為考生提供全真的模擬考試環(huán)境和過往真題，而TPO題庫也是有著不斷的更新。在托福閱讀的備考過程中，除了大量的閱讀之外，全面了解托福閱讀的題型和解題方法也都是非常重要的環(huán)節(jié)。而對于很多備考托福的學生來說，TPO往往就是一個首先的備考材料。今天，小編就為大家?guī)�來托福TPO47閱讀真題解析：Passage 1。

Coral Reefs

托福TPO47閱讀Passage 1 ——Paragraph 1  【在線咨詢】

An important environment that is more or less totally restricted to the intertropical zone is the coral reef. Coral reefs are found where the ocean water temperature is not less than 21 °C, where there is a firm substratum, and where the seawater is not rendered too dark by excessive amounts of river-borne sediment. They will not grow in very deep water, so a platform within 30 to 40 meters of the surface is a necessary prerequisite for their development. Their physical structure is dominated by the skeletons of corals, which are carnivorous animals living off zooplankton. However, in addition to corals there are enormous quantities of algae, some calcareous, which help to build the reefs. The size of reefs is variable. Some atolls are very large—Kwajelein in the Marshall Islands of the South Pacific is 120 kilometers long and as much as 24 kilometers across-but most are very much smaller, and rise only a few meters above the water. The 2,000 kilometer complex of reefs known as the Great Barrier Reef, which forms a gigantic natural breakwater off the northeast coast of Australia, is by far the greatest coral structure on Earth.

1. According to paragraph 1, all of the following are needed for the growth of coral reefs except? 【否定事實信息題】
A. a solid base to grow on
B. exposure to light
C. the presence of river-borne sediment
D. ocean temperatures of 21 °C or higher
答案：C

解析：原文Coral reefs are found where the ocean water temperature is not less than 21 °C，說明溫度不能低于21°C，對應選項D中：21 °C or higher，原文where there is a firm substratum，說明基礎(chǔ)一定要堅實，對應選項A中：a solid base，原文the seawater is not rendered too dark，說明不能太暗，對應選項B中：light。過多的沉淀物會遮住光不利于珊瑚礁生長，選項C錯在sediment。

2. the word “prerequisite” in the passage is closest in meaning to【詞匯題】
A. precaution
B. preparation
C. requirement
D. achievement
答案：C

解析：prerequisite, 先決條件。C選項必要條件，為同義替換，所以C選項正確。

3. According to paragraph 1, algae are important because【事實信息題】
A. they help build coral reefs
B. they are the dominant type of sea life living on the reefs
C. they compete with coral for zooplankton
D. they are an important source of food available to corals
答案：A

解析：原文However, … there are enormous quantities of algae … which help to build the reefs，說明海藻幫助建造珊瑚礁，對應選項A中：they help build coral reefs。

4. The word “complex” in the passage is closest in meaning to? 【詞匯題】
A. extension
B. system
C. region
D. variety
答案：B

解析：complex, 復合體。B選項系統(tǒng)，為同義替換，所以B選項正確。

托福TPO47閱讀Passage 1 —— Paragraph 2    【在線咨詢】

Coral reefs have fascinated scientists for almost 200 years, and some of the most pertinent observations of them were made in the 1830s by Charles Darwin on the voyage of the Beagle. He recognized that there were three major kinds: fringing reefs, barrier reefs, and atolls; and he saw that they were related to each other in a logical and gradational sequence. A fringing reef is one that lies close to the shore of some continent or island. Its surface forms an uneven and rather rough platform around the coast, about the level of low water, and its outer edge slopes downwards into the sea. Between the fringing reef and the land there is sometimes a small channel or lagoon. When the lagoon is wide and deep and the reef lies at some distance from the shore and rises from deep water it is called a barrier reef. An atoll is a reef in the form of a ring or horseshoe with a lagoon in the center.

5. According to paragraph 2, how did Charles Darwin contribute to the understanding of coral reefs? 【事實信息題】
A. He identified the main types of coral reef and explained how they were related.
B. He discovered the existence of coral reefs on a scientific voyage.
C. He proved that reefs are mostly located very close to the shore.
D. He saw the importance of reefs for the support of other marine life.
答案：A

解析：原文He recognized that there were three major kinds: …; and he saw that they were related to each other ...，說明達爾文識別三種珊瑚礁并且解釋了他們的相關(guān)性，對應選項A中：He identified the main types of coral reef and explained how they were related。

6. The word “pertinent” in the passage is closest in meaning to【詞匯題】
A. extraordinary
B. relevant
C. intelligent
D. famous
答案：B

解析：pertinent, 相關(guān)的。B選項有關(guān)的，為同義替換，所以B選項正確。

7. According to paragraph 2, which of the following is NOT characteristics of a barrier reef? 【否定事實信息題】
A. It is located away from the shore of the neighboring land.
B. It is separated from neighboring land by a wide channel.
C. It is located in deep ocean water.
D. It surrounds a small, central lagoon.
答案：D

解析：原文An atoll is a reef … with a lagoon in the center，說明中間有瀉湖的是環(huán)礁，所以選項D不是堡礁的特點。

托福TPO47閱讀Passage 1 —— Paragraph 3    【在線咨詢】

Darwin s theory was that the succession from one coral reef type to another could be achieved by the upward growth of coral from a sinking platform, and that there would be a progression from a fringing reef, through the barrier reef stage until, with the disappearance through subsidence (sinking) of the central island, only a reef-enclosed lagoon or atoll would survive. A long time after Darwin put forward this theory, some deep boreholes were drilled in the Pacific atolls in the 1950s. The drill holes passed through more than a thousand meters of coral before reaching the rock substratum of the ocean floor, and indicated that the coral had been growing upward for tens of millions of years as Earth's crust subsided at a rate of between 15 and 51 meters per million years. Darwin s theory was therefore proved basically correct. There are some submarine islands called guyots and seamounts, in which subsidence associated with sea-floor spreading has been too speedy for coral growth to keep up.

8. 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. 【句子簡化題】
A. Darwin claimed that, of the three types of coral reefs, only an atoll would be able to survive on a sinking platform.
B. Darwin recognized that coral reefs achieved success by growing upward from a sinking land platform and becoming an atoll.
C. Darwin argued that as a coral reef grew up from a sinking island, it would become a fringing reef, then a barrier reef, and finally, with the disappearance of the island, an atoll.
D. Darwin’s theory helped explain the disappearance of a number of islands by showing how coral reef growth caused them to sink below the ocean surface.
答案：C

解析：劃線句子意為珊瑚礁從下沉的島嶼上長出來，然后變成裙礁，再變成堡礁，最后島嶼消失變成環(huán)礁，對應選項C中：Darwin … as a coral reef … a sinking island, … fringing reef, … barrier reef, and … disappearance of the island, an atoll.

9. Which of the following can be inferred from paragraph 3 about the Pacific atolls? 【推理題】
A. They were once fringing reefs around the coasts of islands.
B. They were first observed by Darwin during his voyage on the Beagle.
C. They will eventually become fringing reefs.
D. They are located where the ocean floor does not sink.
答案：A

解析：原文A long time after Darwin put forward this theory, some deep boreholes were drilled in the Pacific atolls in the 1950s. … and indicated that the coral … growing upward … as Earth's crust subsided .... Darwin s theory was therefore proved basically correct，說明太平洋環(huán)礁隨著地球地殼減少慢慢上漲而形成的，證明達爾文理論正確，所以太平洋環(huán)礁最初就是圍繞島嶼的裙礁，對應選項A中：They were once fringing reefs around the coasts of islands。

10. Why does the passage provide the information that the drill holes in the Pacific atolls passed through more than a thousand meters of coral before reaching the rock substratum of the ocean floor? 【組織結(jié)構(gòu)題】
A. To emphasize that according to Darwin’s view coral can grow at great depths
B. To indicate how scientists knew the rate at which Earth’s crust had subsided
C. To support the claim that coral reefs take millions of years to form
D. To present the evidence that confirmed Darwin’s account of coral reef evolution
答案：D

解析：原文Darwin s theory was therefore proved basically correct，說明舉例太平洋環(huán)礁就是為了證明達爾文理論正確，對應選項D中：To present the evidence that confirmed Darwin’s account of coral reef evolution。

托福TPO47閱讀Passage 1 —— Paragraph 4    【在線咨詢】

Like mangrove swamps, coral reefs are extremely important habitats. Their diversity of coral genera is greatest in the warm waters of the Indian Ocean and the western Pacific. Indeed, they have been called the marine version of the tropical rain forest, rivaling their terrestrial counterparts in both richness of species and biological productivity. They also have significance because they provide coastal protection, opportunities for recreation, and are potential sources of substances like medicinal drugs. At present they are coming under a variety of threats, of which two of the most important are dredging and the effects of increased siltation brought about by accelerated erosion from neighboring land areas.

11. According to paragraph 4, why have coral reefs been compared to tropical rain forests? 【修辭目的題】
A. Both are located near the Indian and western Pacific Oceans.
B. Both are home to a wide variety of species.
C. Both play an important role in protecting coastal islands.
D. Both are threatened by the erosion of nearby land.
答案：B

解析：原文Indeed, they have been called the marine version of the tropical rain forest, rivaling their terrestrial counterparts in both richness of species and biological productivity，說明二者可以相比是因為物種都很豐富，對應選項B中：Both are home to a wide variety of species。

12. The word “potential” in the passage is closest in meaning to【詞匯題】
A. powerful
B. possible
C. valuable
D. reliable
答案：B

解析：potential, 潛在的。B選項可能的，為同義替換，所以B選項正確。

13. Look at the four squares [■] that indicate where the following sentence could be added to the passage. 【句子插入題】
Yet because many coral reef organisms can tolerate only a narrow range of environmental conditions, reefs are sensitive to damage from environmental changes.
Where would the sentence best fit? Click on a square [■] to add the sentence to the passage.
Like mangrove swamps, coral reefs are extremely important habitats. Their diversity of coral genera is greatest in the warm waters of the Indian Ocean and the western Pacific. ■ Indeed, they have been called the marine version of the tropical rain forest, rivaling their terrestrial counterparts in both richness of species and biological productivity. ■They also have significance because they provide coastal protection, opportunities for recreation, and are potential sources of substances like medicinal drugs. ■At present they are coming under a variety of threats, of which two of the most important are dredging and the effects of increased siltation brought about by accelerated erosion from neighboring land areas. ■
答案：C

解析：待插入句子意為但是珊瑚礁很容易因為環(huán)境改變而受到傷害，因為上面的微生物對于生存環(huán)境要求很高�？梢酝ㄟ^yet推測這句句子前面說的是珊瑚礁非常好，對應句子They also have significance because they provide coastal protection, opportunities for recreation, and are potential sources of substances like medicinal drugs，還可以推出這句句子之后說的是可能受到的傷害，對應句子At present they are coming under a variety of threats, of which two of the most important are dredging and the effects of increased siltation brought about by accelerated erosion from neighboring land areas，所以句子放在C位置最為合適。

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. 【概要小結(jié)題】
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.
Coral reefs constitute an important tropical environment that provides habitat for a rich variety of ocean life.
Answer Choices
A. Coral reefs are structures made by living creatures and can grow only in specific ocean conditions.
B. Although atolls can sometimes grow to large proportions, barrier reefs are by far the largest coral structures.
C. Mangrove swamps are as important as coral reefs as the habitat for numerous plant and animal species.
D. Coral reefs are classified as fringing, barrier, or atoll, all of which are linked in a chain of progressive development.
E. Although coral reefs are important to humans in several ways, they are currently threatened by dredging and mud from erosion.
F. Fringing reefs lie close to the shore of continents and islands, forming a transition zone between the land mass and the sea.
答案：ADE

解析：原文首先介紹珊瑚礁的組成以及生存環(huán)境要求，對應選項A中：Coral reefs … living creatures … specific ocean conditions，然后介紹三種珊瑚礁以及它們的進化順序，對應選項D中：Coral reefs are classified as fringing, barrier, or atoll, … a chain of progressive development，最后介紹珊瑚礁的好處以及它們受到的威脅，對應選項E中：Although coral reefs are important …, … threatened by dredging and mud from erosion。

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