『新东方在线托福听力』为托福考生准备了ETS托福TPO/Official 47 Passage 3阅读练习，TPO/Official 47 Passage 3原文答案解析，TPO/Official 47 Passage 3阅读原文练习音频翻译。

托福TPO/Official 47 Passage 3阅读原文题目答案及解析-新东方托福官方网校手机版

珊瑚礁或多或少完全局限于热带地区的重要环境。

An important environment that is more or less totally restricted to the intertropical zone is the coral reef.

在海水温度不低于21°C，有牢固的基质，海水不会因过多的河床沉积物而变得太暗的情况下，就可以找到珊瑚礁。

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.

它们不会在很深的水中生长，所以在离水面30-40米的地方建一个平台是它们生长的必要前提。

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.

它们的物理结构以珊瑚骨骼为主导，珊瑚是以浮游动物为食的食肉动物。

Their physical structure is dominated by the skeletons of corals, which are carnivorous animals living off zooplankton.

然而，除了珊瑚之外，还有大量的藻类，其中一些是钙质的，它们有助于建造珊瑚礁。

However, in addition to corals there are enormous quantities of algae, some calcareous, which help to build the reefs.

一些环礁非常大—南太平洋马绍尔群岛的夸耶林长120公里，跨度最大为24公里—但大多数环礁要小得多，并且仅高出水面几米。

Some atolls are very large—Kwajalein 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.

这座长达2000公里的礁石群被称为大堡礁，它是澳大利亚东北沿海的一个巨大的天然防波堤，是迄今为止地球上最大的珊瑚结构。

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.

近200年来，珊瑚礁一直吸引着科学家，一些对珊瑚礁最为相关的观测是由查尔斯·达尔文在19世纪30年代，乘坐小猎犬号航行时完成的。

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.

他认识到，珊瑚礁主要有三种类型：边缘礁、堡礁和环礁；他发现它们之间是按逻辑和层次顺序联系在一起的。

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.

边缘礁是位于某个大陆或岛屿的海岸附近的礁石。

A fringing reef is one that lies close to the shore of some continent or island.

它的表面在低水位附近沿海岸形成一个不平坦且相当粗糙的平台，其外缘向下倾斜到海中。

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.

在边缘礁和陆地之间，有时会有一个小河道或泻湖。

Between the fringing reef and the land there is sometimes a small channel or lagoon.

当泻湖又宽又深，礁石位于离海岸一定的距离并从深水中升起时，被称为堡礁。

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.

环礁是环形或马蹄形的礁石，中心是泻湖。

An atoll is a reef in the form of a ring or horseshoe with a lagoon in the center.

达尔文的理论是，从下沉的平台向上生长，珊瑚可以实现从一种珊瑚礁类型到另一种珊瑚礁的演替，并且有一个过程：从边缘珊瑚礁到堡礁阶段，直到消失到中心岛的沉陷（沉没）中，只有礁石围成的泻湖或环礁才能幸存。

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.

在达尔文提出这一理论很长时间之后，20世纪50年代人们在太平洋环礁上钻了一些深孔。

A long time after Darwin put forward this theory, some deep boreholes were drilled in the Pacific atolls in the 1950s.

钻孔在到达海床的岩石底层之前已经穿过了1000多米的珊瑚，这表明随着地壳以每百万年15至51米的速度消退，珊瑚已经向上生长了几千万年。

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.

因此，达尔文的理论被证明是基本正确的。

Darwin’s theory was therefore proved basically correct.

有一些海底岛屿叫做盖奥提岛和海山，其中由于海底扩张引起的下沉速度太快，珊瑚的生长无法跟上。

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.

像红树林沼泽一样，珊瑚礁是极其重要的栖息地。

Like mangrove swamps, coral reefs are extremely important habitats.

它们的珊瑚属的多样性在印度洋和西太平洋的温暖水域最为丰富。

Their diversity of coral genera is greatest in the warm waters of the Indian Ocean and the western Pacific.

实际上，它们被称为热带雨林的海洋版本，在物种丰富性和生物生产力方面都可以与陆地上的同类植物相媲美。

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.

它们还具有重要意义，因为它们提供了海岸防护、休闲娱乐的机会，而且是药物等物质的潜在来源。

They also have significance because they provide coastal protection, opportunities for recreation, and are potential sources of substances like medicinal drugs.

目前，它们正面临着各种各样的威胁，其中最重要的两项是疏浚和邻近地区加速侵蚀所带来的泥沙淤积增加的影响。

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.

According to paragraph 1, all of the following are needed for the growth of coral reefs EXCEPT

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

According to paragraph 2, how did Charles Darwin contribute to the understanding of coral reefs?

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

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.

Which of the following can be inferred from paragraph 3 about the Pacific atolls?

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?

According to paragraph 4, why have coral reefs been compared to tropical rain forests?

Look at the four squares  that indicate where the following sentence could be added to the passage. 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.

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.

Coral Reefs 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—Kwajalein 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. 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. 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. 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.