托福TPO47阅读真题解析：Passage 1

TPO，即toefl Practice Online的首写字母，就是托福在线练习的意思，TPO可以为考生提供全真的模拟考试环境和过往真题，而TPO题库也是有着不断的更新。在托福阅读的备考过程中，除了大量的阅读之外，全面了解托福阅读的题型和解题方法也都是非常重要的环节。而对于很多备考托福的学生来说，TPO往往就是一个首先的备考材料。今天，小编就为大家带来托福TPO47阅读真题解析：Passage 1。

Coral Reefs

托福TPO47阅读Passage 1 ——Paragraph 1  【在线咨询】

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? 【否定事实信息题】
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，说明温度不能低于21°C，对应选项D中：21 °C or higher，原文where there is a firm substratum，说明基础一定要坚实，对应选项A中：a solid base，原文the seawater is not rendered too dark，说明不能太暗，对应选项B中：light。过多的沉淀物会遮住光不利于珊瑚礁生长，选项C错在sediment。

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

解析：prerequisite, 先决条件。C选项必要条件，为同义替换，所以C选项正确。

3. According to paragraph 1, algae are important because【事实信息题】
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，说明海藻帮助建造珊瑚礁，对应选项A中：they help build coral reefs。

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

解析：complex, 复合体。B选项系统，为同义替换，所以B选项正确。

托福TPO47阅读Passage 1 —— Paragraph 2    【在线咨询】

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? 【事实信息题】
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 ...，说明达尔文识别三种珊瑚礁并且解释了他们的相关性，对应选项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【词汇题】
A. extraordinary
B. relevant
C. intelligent
D. famous
答案：B

解析：pertinent, 相关的。B选项有关的，为同义替换，所以B选项正确。

7. According to paragraph 2, which of the following is NOT characteristics of a barrier reef? 【否定事实信息题】
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，说明中间有泻湖的是环礁，所以选项D不是堡礁的特点。

托福TPO47阅读Passage 1 —— Paragraph 3    【在线咨询】

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. 【句子简化题】
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：划线句子意为珊瑚礁从下沉的岛屿上长出来，然后变成裙礁，再变成堡礁，最后岛屿消失变成环礁，对应选项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? 【推理题】
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，说明太平洋环礁随着地球地壳减少慢慢上涨而形成的，证明达尔文理论正确，所以太平洋环礁最初就是围绕岛屿的裙礁，对应选项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? 【组织结构题】
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，说明举例太平洋环礁就是为了证明达尔文理论正确，对应选项D中：To present the evidence that confirmed Darwin’s account of coral reef evolution。

托福TPO47阅读Passage 1 —— Paragraph 4    【在线咨询】

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? 【修辞目的题】
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，说明二者可以相比是因为物种都很丰富，对应选项B中：Both are home to a wide variety of species。

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

解析：potential, 潜在的。B选项可能的，为同义替换，所以B选项正确。

13. Look at the four squares [■] that indicate where the following sentence could be added to the passage. 【句子插入题】
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：待插入句子意为但是珊瑚礁很容易因为环境改变而受到伤害，因为上面的微生物对于生存环境要求很高。可以通过yet推测这句句子前面说的是珊瑚礁非常好，对应句子They also have significance because they provide coastal protection, opportunities for recreation, and are potential sources of substances like medicinal drugs，还可以推出这句句子之后说的是可能受到的伤害，对应句子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位置最为合适。

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.
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：原文首先介绍珊瑚礁的组成以及生存环境要求，对应选项A中：Coral reefs … living creatures … specific ocean conditions，然后介绍三种珊瑚礁以及它们的进化顺序，对应选项D中：Coral reefs are classified as fringing, barrier, or atoll, … a chain of progressive development，最后介绍珊瑚礁的好处以及它们受到的威胁，对应选项E中：Although coral reefs are important …, … threatened by dredging and mud from erosion。

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