托福TPO22题目解析1

　　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

　　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，第一个并列两个句子，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

　　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.

　　O It 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：段落第一句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 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.

　　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很多一拉滩涂的鱼类和水禽的沼泽地，填入“改变”，选2

　　Paragraph 6: 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.

　　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 ...

　　参考译文：

　　米草属植物

　　互花米草，俗称网茅，是一种冬季枯萎的多年生开花植物，原产自大西洋沿岸和美国的墨西哥湾。它是这些海岸地区低海拔盐碱地的优势本地种，生长于潮汐带(有时淹没在水中，有时暴露在空气中的区域)。

　　这 些天然的盐碱地位于海洋环境下最肥沃的生境中。涨潮时会给沼泽带来营养丰富的海水，使得食物有可能获得高产。随着海草和沼泽禾草叶子的死亡，细菌将植物体 分解，昆虫、小型虾状浮游生物、招潮蟹和沼泽蜗牛吃掉了腐烂的植物组织，消化后排出富含营养的排泄物。沼泽里生活着无数的昆虫，它们以活着或死去的网茅组 织为食，红翼歌鸫、麻雀、啮齿动物、兔子以及鹿都直接食用网茅。每一个潮汐周期都会将植物带到近海海水中，它们可以被潮水下的生物所利用。

　　米 草属植物是极具竞争力的植物。它主要通过地下茎向四周扩展，当根系或整株植物漂到一个区域并扎下根来，或者当种子漂到一个适合的地方并发芽，就会形成新的 群落。从泥沙地到卵砾石地，米草属植物都能生长，其耐盐度从接近淡水(0.05%)到盐水(3.5%)。由于沼泽沉积物里缺乏氧气，因而含有很多的硫化 物，对多数植物而言是有毒的。米草属植物具有能够吸收硫化物并将其转换成为硫酸盐——一种植物可以利用的硫形式的能力。这种能力使得米草属植物能够在沼泽 环境中生存。另一个适应性优势就是米草属植物比其它植物能更为有效的利用二氧化碳的能力。

　　这些特征使得在河口处自然生长出的米草属植物成为 了该地重要的组成部分。植物起到了稳定器和沉积物收集器的作用，而且还充当了河口鱼类和贝类的哺育场所。一旦落地生根，一片米草属植物就开始截留沉积物， 改变基质的海拔高度，最终这片米草属植物会逐渐被更高海拔的微咸淡水植物所取代，发展成了一个高海拔的沼泽系统。

　　1894年，为了将牡蛎从 东海岸转移到华盛顿州，米草属植物被打包运往华盛顿州。由于缺少捕食性昆虫，网茅沿着西海岸华盛顿州的潮汐河口缓慢而稳定地传播开来，排挤本地植物，并通 过截留沉积物极大地改变了当地的景观。米草属植物改造了沿海滩涂，将它们转变成不适合很多依赖于滩涂的鱼类和水禽生活的高海拔沼泽。米草属植物已经妨碍了 牡蛎的打捞以及珍宝蟹的养殖，它干扰了海滩和海滨的休憩用途。人们将米草属植物移栽到英国和新西兰用于改良土地以及稳定海岸线。在新西兰，米草属植物扩散 得很快，它改变了沼泽，将沼泽地的边缘变成了广阔的盐渍草地，并减少了在沼泽生活的鸟类和动物的数量。

　　为了在米草属植物自然生境以外控制它 的扩散，人们尝试了焚烧、水淹、用黑色的帆布或塑料布遮挡阳光、用疏浚物料或者粘土使其窒息、喷撒除草剂以及反复割草的方法。在新西兰和英国只取得了微不 足道的成效，华盛顿州的管理项目尝试了很多此类方法，目前正在使用除草剂草甘膦控制它的传播。已经开展了相关工作确定用昆虫进行生物防止的有效性，但是真 正能够采取有效的生物防治还需要很多年。即使是付出巨大的努力，我们仍然怀疑完全从非原生境中根除米草属植物的可能性，因为在过去的100到200年间， 它已经成为了这些海岸线地带和河口的主要组成部分。