同学们备考托福，都在寻找好的参考资料书。北京新航道托福频道提醒大家，TPO是，即使没时间看别的也不可不看TPO，真题是托福考试的标尺和模型，帮助考生熟悉考试的题型。下面请看托福频道为大家奉上的托福TPO22阅读篇原文及题目详解。

 

　　Spartina

　　Spartina alterniflora, known as cordgrass, is a deciduous, perennial flowering plant native to the Atlantic coast and the Gulf Coast of the United States. It is the dominant native species of the lower salt marshes along these coasts, where it grows in the intertidal zone (the area covered by water some parts of the day and exposed others).

　　These natural salt marshes are among the most productive habitats in the marine environment. Nutrient-rich water is brought to the wetlands during each high tide, making a high rate of food production possible. As the seaweed and marsh grass leaves die, bacteria break down the plant material, and insects, small shrimplike organisms, fiddler crabs, and marsh snails eat the decaying plant tissue, digest it, and excrete wastes high in nutrients. Numerous insects occupy the marsh, feeding on living or dead cordgrass tissue, and redwing blackbirds, sparrows, rodents, rabbits, and deer feed directly on the cordgrass. Each tidal cycle carries plant material into the offshore water to be used by the subtidal organisms.

　　Spartina is an exceedingly competitive plant. It spreads primarily by underground stems; colonies form when pieces of the root system or whole plants float into an area and take root or when seeds float into a suitable area and germinate. Spartina establishes itself on substrates ranging from sand and silt to gravel and cobble and is tolerant of salinities ranging from that of near freshwater (0.05 percent) to that of salt water (3.5 percent). Because they lack oxygen, marsh sediments are high in sulfides that are toxic to most plants. Spartina has the ability to take up sulfides and convert them to sulfate, a form of sulfur that the plant can use; this ability makes it easier for the grass to colonize marsh environments. Another adaptive advantage is Spartina’s ability to use carbon dioxide more efficiently than most other plants.

　　These characteristics make Spartina a valuable component of the estuaries where it occurs naturally. The plant functions as a stabilizer and a sediment trap and as a nursery area for estuarine fish and shellfish. Once established, a stand of Spartina begins to trap sediment, changing the substrate elevation, and eventually the stand evolves into a high marsh system where Spartina is gradually displaced by higher-elevation, brackish-water species. As elevation increases, narrow, deep channels of water form throughout the marsh. Along the east coast Spartina is considered valuable for its ability to prevent erosion and marshland deterioration; it is also used for coastal restoration projects and the creation of new wetland sites.

　　Spartina was transported to Washington State in packing materials for oysters transplanted from the east coast in 1894. Leaving its insect predators behind, the cordgrass has been spreading slowly and steadily along Washington’s tidal estuaries on the west coast, crowding out the native plants and drastically altering the landscape by trapping sediment. Spartina modifies tidal mudflats, turning them into high marshes inhospitable to the many fish and waterfowl that depend on the mudflats. It is already hampering the oyster harvest and the Dungeness crab fishery, and it interferes with the recreational use of beaches and waterfronts. Spartina has been transplanted to England and to New Zealand for land reclamation and shoreline stabilization. In New Zealand the plant has spread rapidly, changing mudflats with marshy fringes to extensive salt meadows and reducing the number and kinds of birds and animals that use the marsh.

　　Efforts to control Spartina outside its natural environment have included burning, flooding, shading plants with black canvas or plastic, smothering the plants with dredged materials or clay, applying herbicide, and mowing repeatedly. Little success has been reported in New Zealand and England;Washington State’s management program has tried many of these methods and is presently using the herbicide glyphosphate to control its spread. Work has begun to determine the feasibility of using insects as biological controls, but effective biological controls are considered years away. Even with a massive effort, it is doubtful that complete eradication of Spartina from nonnative habitats is possible, for it has become an integral part of these shorelines and estuaries during the last 100 to 200 years.

　　Paragraph 1: Spartina alterniflora, known as cordgrass, is a deciduous, perennial flowering plant native to the Atlantic coast and the Gulf Coast of the United States. It is the dominant native species of the lower salt marshes along these coasts, where it grows in the intertidal zone (the area covered by water some parts of the day and exposed others).

　　1. According to paragraph 1, each of the following is true of Spartina alrerniflora EXCEPT:

　　O It rarely flowers in salt marshes.

　　O It grows well in intertidal zones.

　　O It is commonly referred to as cordgrass.

　　O It occurs naturally along the Gulf Coast and the Atlantic coast of the United States.

　　排除题

　　定位词：Spartina alrerniflora

　　解析：Spartina alterniflora, known as cordgrass, is a deciduous, perennial flowering plant native to the Atlantic coast and the Gulf Coast of the United States. It is the dominant native species of the lower salt marshes along these coasts, where it grows in the intertidal zone

　　2,3,4都说到，唯独1原文说生长在低海拔盐碱度地区，而不是很少出现在盐碱度地区，选择1

　　Paragraph 2: These natural salt marshes are among the most productive habitats in the marine environment. Nutrient-rich water is brought to the wetlands during each high tide, making a high rate of food production possible. As the seaweed and marsh grass leaves die, bacteria break down the plant material, and insects, small shrimplike organisms, fiddler crabs, and marsh snails eat the decaying plant tissue, digest it, and excrete wastes high in nutrients. Numerous insects occupy the marsh, feeding on living or dead cordgrass tissue, and redwing blackbirds, sparrows, rodents, rabbits, and deer feed directly on the cordgrass.Each tidal cycle carries plant material into the offshore water to be used by the subtidal organisms.

　　2. According to paragraph 2, a major reason why natural salt marshes are so productive is that they are

　　O inhabited by long-lived seaweed and marsh grasses that reproduce gradually

　　O kept clear of excess plant material by the tides

　　O regularly supplied with high levels of nutrients

　　O home to a wide variety of different species of grasses

　　细节题

　　定位词：natural salt marshes are so productive

　　解析：These natural salt marshes are among the most productive habitats in the marine environment. Nutrient-rich water is brought to the wetlands during each high tide, making a high rate of food production possible. 定期有高营养注入，选3

　　3. Which of the sentences below best express the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.

　　O Insects feed only on dead cordgrass, while most other marsh inhabitants feed on live

　　cordgrass.

　　O The marsh is a good habitat for insects, but a relatively poor one for birds and

　　animals.

　　O Although cordgrass provides food for birds and animals, it gives insects both food and a place to live.

　　O Cordgrass provides food for numerous insects, birds, and other animals.

　　句子简化题

　　解析：Numerous insects occupy the marsh, feeding on living or dead cordgrass tissue, and redwing blackbirds, sparrows, rodents, rabbits, and deer feed directly on the cordgrass.

　　逻辑关系：两个and并列关系，个并列两个句子，第二个并列第二个句子的主语。动作都是feed on;各种昆虫占据沼泽地，以活的或者死的带状草地组织为食，同时红翼鸫，画眉，麻雀，啮齿动物和兔子直接以带状草地为食。

　　O Insects feed only on dead cordgrass, while most other marsh inhabitants feed on live cordgrass.昆虫死的活的都吃，没有说其他的吃死的还是活的

　　O The marsh is a good habitat for insects, but a relatively poor one for birds and animals.没有转折关系

　　O Although cordgrass provides food for birds and animals, it gives insects both food and a place to live.没有让步关系，也没提到提供地方居住,来源：北京新航道托福频道

　　O Cordgrass provides food for numerous insects, birds, and other animals.并列关系，内容符合

　　Paragraph 3: Spartina is an exceedingly competitive plant. It spreads primarily by underground stems; colonies form when pieces of the root system or whole plants float into an area and take root or when seeds float into a suitable area and germinate. Spartina establishes itself on substrates ranging from sand and silt to gravel and cobble and is tolerant of salinities ranging from that of near freshwater (0.05 percent) to that of salt water (3.5 percent). Because they lack oxygen, marsh sediments are high in sulfides that are toxic to most plants. Spartina has the ability to take up sulfides and convert them to sulfate, a form of sulfur that the plant can use; this ability makes it easier for the grass to colonize marsh environments. Another adaptive advantage is Spartina’s ability to use carbon dioxide more efficiently than most other plants.

　　4. What is the organizational structure of paragraph 3?

　　O It makes a general claim about Spartina and then provides specific evidence to defend that claim against objections to the claim.

　　OIt presents a general characterization of Spartina and then describes particular features on which this characterization is based.

　　O It reports a widely held view about Spartina and then considers evidence both for and against that view.

　　O It presents a general hypothesis about Spartina and then lists specific evidence that disputes that hypothesis.

　　段落结构题

　　解析：段落句Spartina is an exceedingly competitive plant，给米草属植物下定义，之后分别介绍它的特点，选2

　　5. The word "exceedingly" in the passage is closest in meaning to

　　O unusually

　　O dangerously

　　O surprisingly

　　O highly

　　词汇题

　　解析：Spartina is an exceedingly competitive plant.用来修饰“有竞争力的”，根据文章可知是“十分”有竞争力的，起到强调作用，选4

　　6. According to paragraph 3, one reason that Spanina is able to compete in marsh environments so successfully is its ability to

　　O alter the substrate in which it grows

　　O convert sulfides into a usable form of sulfur

　　O grow and produce seeds while floating on the surface of the water

　　O produce carbon dioxide with great efficiency

　　细节题

　　定位词：marsh environments，its ability

　　解析：Spartina has the ability to take up sulfides and convert them to sulfate, a form of sulfur that the plant can use; this ability makes it easier for the grass to colonize marsh environments.因为它可以将吸收硫化物，并转换成为硫酸盐。选2

　　Paragraph 4: These characteristics make Spartina a valuable component of the estuaries where it occurs naturally. The plant functions as a stabilizer and a sediment trap and as a nursery area for estuarine fish and shellfish. Once established, a stand of Spartina begins to trap sediment, changing the substrate elevation, and eventually the stand evolves into a high marsh system where Spartina is gradually displaced by higher-elevation, brackish-water species. As elevation increases, narrow, deep channels of water form throughout the marsh. Along the east coast Spartina is considered valuable for its ability to prevent erosion and marshland deterioration; it is also used for coastal restoration projects and the creation of new wetland sites.

　　7. Paragraph 4 suggests that where Spanina occurs naturally, an established stand of it will eventually

　　O create conditions in which it can no longer survive

　　O get washed away by water flowing through the deep channels that form around it

　　O become adapted to brackish water

　　O take over other grass species growing in the area

　　推断题

　　定位词：an established stand

　　解析：Once established, a stand ofSpartina begins to trap sediment, changing the substrate elevation, and eventually the stand evolves into a high marsh system where Spartina is gradually displaced by higher-elevation, brackish-water species.一旦米草植物定下来，就开始吸收沉淀物，改变基质的海拔高度，最终这地方会更高海拔的微咸淡水植物取代，发展成一个高海拔沼泽地。选1，创造是自己不能存活的条件

　　8. According to paragraph 4, in its natural habitats, Spanina helps estuaries by

　　O controlling marshland decline

　　O decreasing the substrate elevation

　　O reducing the brackishness of the water

　　O increasing the flow of water into the estuary

　　细节题

　　定位词：Spanina helps estuaries

　　解析：Along the east coast Spartina is considered valuable for its ability to prevent erosion and marshland deterioration;帮助阻止沼泽地的退化，选1

　　Paragraph 5: Spartina was transported to Washington State in packing materials for oysters transplanted from the east coast in 1894. Leaving its insect predators behind, the cordgrass has been spreading slowly and steadily along Washington’s tidal estuaries on the west coast, crowding out the native plants and drastically altering the landscape by trapping sediment. Spartina modifiestidal mudflats, turning them into high marshes inhospitable to the many fish and waterfowl that depend on the mudflats. It is already hampering the oyster harvest and the Dungeness crab fishery, and it interferes with the recreational use of beaches and waterfronts. Spartina has been transplanted to England and to New Zealand for land reclamation and shoreline stabilization. In New Zealand the plant has spread rapidly, changing mudflats with marshy fringes to extensive salt meadows and reducing the number and kinds of birds and animals that use the marsh.

　　9. The word "modifies" in the passage is closest in meaning to

　　O creates

　　O changes

　　O grows on

　　O breaks down

　　词汇题

　　解析：Spartina modifies tidal mudflats, turning them into high marshes inhospitable to the many fish and waterfowl that depend on the mudflats.上下文关系，米草植物___沿海滩涂，将他们转变成不适合一拉滩涂的鱼类和水禽的沼泽地，填入“改变”，选2

　　Paragraph 6: Effortsto control Spartina outside its natural environment have included burning, flooding, shading plants with black canvas or plastic, smothering the plants with dredged materials or clay, applying herbicide, and mowing repeatedly. Little success has been reported in New Zealand and England;Washington State’s management program has tried many of these methods and is presently using the herbicide glyphosphate to control its spread. Work has begun to determine the feasibility of using insects as biological controls, but effective biological controls are considered years away. Even with a massive effort, it is doubtful that complete eradication of Spartina from nonnative habitats is possible, for it has become an integral part of these shorelines and estuaries during the last 100 to 200 years.

　　10. The word "Efforts" in the passage is closest in meaning to

　　O Laws

　　O Suggestions

　　O Attempts

　　O Failures

　　词汇题：

　　解析：Efforts to control Spartina outside its natural environment have included burning, flooding, shading plants with black canvas or plastic, smothering the plants with dredged materials or clay, applying herbicide, and mowing repeatedly.之后都是控制米草植物的方法，所以选择3

　　11. According to paragraph 5, Spanina negatively affects wildlife in estuaries by

　　O trapping fish and waterfowl in sediment

　　O preventing oysters from transplanting successfully

　　O turning mudflats into high marshes and salt meadows

　　O expanding the marshy fringes of salt meadows

　　细节题

　　定位词：negatively affects wildlife in estuaries

　　解析：Spartina modifies tidal mudflats, turning them into high marshes inhospitable to the many fish and waterfowl that depend on the mudflats. It is already hampering the oyster harvest and the Dungeness crab fishery, and it interferes with the recreational use of beaches and waterfronts.

　　“hamper”“interfere”强调spartina改变沿海滩涂的副作用，选3

　　12. According to paragraph 6, each of the following methods has been used in attempts to control Spanina EXCEPT

　　O flooding plants

　　O cutting plants down repeatedly

　　O applying herbicides

　　O introducing predatory insects

　　排除题

　　定位词：methods has been used in attempts to control Spanina

　　解析：Efforts to control Spartina outside its natural environment have included burning,flooding, shading plants with black canvas or plastic, smothering the plants with dredged materials or clay, applying herbicide, and mowing repeatedly.

　　1,2,3都提到，选择4

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

　　Spartina is particularly able to tolerate high salinities because salt glands on the surface of the leaves remove the salt from the plant sap.

　　Where would the sentence best fit?

　　Spartina is an exceedingly competitive plant. It spreads primarily by underground stems; colonies form when pieces of the root system or whole plants float into an area and take root or when seeds float into a suitable area and germinate. Spartina establishes itself on substrates ranging from sand and silt to gravel and cobble and is tolerant of salinities ranging from that of near freshwater (0.05 percent) to that of salt water (3.5 percent). Because they lack oxygen, marsh sediments are high in sulfides that are toxic to most plants. Spartina has the ability to take up sulfides and convert them to sulfate, a form of sulfur that the plant can use; this ability makes it easier for the grass to colonize marsh environments. Another adaptive advantage is Spartina’s ability to use carbon dioxide more efficiently than most other plants.

　　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.

　　Spanina alrerniflora, or cordgrass, is the dominant native species in salt marshes along the Atlantic coast and the Gulf Coast of the United States.

　　Click on 3 answers.

　　O Spartina is very well adapted to conditions in salt marshes, where it plays a valuable role in stabilizing them and making them highly productive marine habitats.

　　O Spartina expands by growing root systems that float on the water’s surface and descend underground, where it finds the nutrients that it needs to germinate.

　　O As a result of its spread in Washington State over the past hundred years. Spartina has now become a threat to native oysters by releasing sediments that contain sulfides into the waters.

　　O The dead leaves of Spartina become food for a wide variety of marine organisms.

　　O Outside its native regions, Spartina can pose serious problems by turning mudflats into high marshes that are inhospitable to many native fish and birds.

　　O Spartina has physiological adaptations that allow it to grow in environments where other plants cannot, making it a very strong competitor that is difficult to control once it is established.

　　总结题

　　解析：分析黑体字：Spanina alrerniflora, or cordgrass, is the dominant native species in salt marshes along the Atlantic coast and the Gulf Coast of the United States.

　　O Spartina is very well adapted to conditions in salt marshes, where it plays a valuable role in stabilizing them and making them highly productive marine habitats.第二段观点，米草植物适合在盐碱沼泽地生存

　　O Spartina expands by growing root systems that float on the water’s surface and descend underground, where it finds the nutrients that it needs to germinate.原文没有提到该信息

　　O As a result of its spread in Washington State over the past hundred years.Spartina has now become a threat to native oysters by releasing sediments that contain sulfides into the waters.细节排除

　　O Thedead leaves of Spartina become food for a wide variety of marine organisms.细节排除

　　O Outside its native regions, Spartina can pose serious problems by turning mudflats into high marshes that are inhospitable to many native fish and birds.第五段观点，米草植物改变滩涂使得鱼类等不能生存

　　O Spartina has physiological adaptations that allow it to grow in environments where other plants cannot, making it a very strong competitor that is difficult to control once it is established.第三段观点，米草植物的优势

　　参考答案：

　　1. A

　　2. C

　　3. D

　　4. B

　　5. D

　　6. B

　　7. A

　　8. A

　　9. B

　　10. C

　　11. C

　　12. D

　　13. C

　　14. Spartina is very well ...

　　Outside its native regions ...

　　Spartina has physiological ...

 

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