托福分类模拟题17及答案解析.doc
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1、托福分类模拟题 17及答案解析(总分:100.00,做题时间:90 分钟)一、READING(总题数:0,分数:0.00)二、TEST 1-1(总题数:1,分数:42.00)Zebra Mollusks? Small, freshwater zebra mollusks have been invading America“s freshwater lakes and rivers for more than fifteen years. The shellfish are native to Russia, the Balkans, and Poland and were originall
2、y found in the areas of the Ural River and the Black, Caspian, and Azov Seas in the 1700s. By the late 1700s and early 1800s, they had spread to many parts of Europe because of the numerous canals. In 1824 these mussels were discovered in Great Britain. Today, they have infested most of Western Euro
3、pe as well as the Scandinavian countries, Ireland and Italy. Zebra mollusks were transported to North America in 1988 in the ballast water of a transatlantic freighter and were discharged into Lake St. Clair, an inland lake in Michigan which connects Lake Erie and Lake Huron. Within four years the m
4、ollusks had infested one lake. Within ten years, more than one hundred lakes had become home for these invaders. Today, these invasive mussels have established themselves in all of the Great Lakes, other inland lakes in Michigan, and the basins of most navigable rivers in the eastern United States i
5、ncluding the Mississippi, Tennessee, Ohio, and Hudson Rivers. Their presence has also recently been detected in the Missouri River basin. ? Zebra mollusks, which get their name from the striped pattern of their shells, are prolific breeders. Females can produce between 30,000 and one million eggs ea
6、ch year. During their planktonic larval stage, young zebra mollusks are the size of a human hair and appear invisible to the human eye and the tiny shellfish can live and feed in many different aquatic habitats, and they can move easily and swiftly in water currents and can drift many miles before s
7、ettling. Adult zebra mollusks live about five years and can survive in fresh water at levels deeper than twenty feet. Once the mollusks reach their adult stage they attach themselves to hard objects in water. Boats, buoys, piers, and fishing gear can be their victims as well as clams, crayfish, turt
8、les and other creatures living in the water. Zebra mollusks also attach themselves to each other to form huge colonies. ? Environmentally, zebra mollusks can be a threat. When they attach themselves to watercraft, the mollusks can cling to the hull or motor or any part of the boat which is immersed
9、in the water. As a result, boats can overheat, have increased drag, and show damaged engine cooling systems. Piers, navigational buoys, and other structures can sink under the weight of the attached mollusks or suffer deterioration and long term damage from the attachment of the shellfish. Many muni
10、cipalities have been required to redesign the intake systems for their city water supplies because mollusks have clogged the intake pipelines. Other communities have resorted to chemicals to treat and prevent zebra mollusk problems. The mollusks can threaten native wildlife and marine life and upset
11、 ecosystems. Marine life is also severely affected by zebra mollusks when the mollusks attach themselves to slow moving animals such as turtles and crayfish or to clams and mussels which are found naturally in fresh water lakes. When the zebra mollusks attach themselves to an object in large numbers
12、, the mollusks are said to be “colonizing.“ Colonizing interferes with the object“s ability to feed itself and its growth, movement, respiration, and reproduction abilities. Despite problems caused by the mollusks, they also provide benefits to polluted bodies of water. As they filter water, they di
13、gest animals and algae that provide food for other fish and animals. The benefit of the filtering process, however, is that water clarity in infested lakes and rivers increases dramatically. These tiny shellfish also provide food for many native birds and fish but they cannot be eaten in amounts gre
14、at enough to control the mollusk population. Zebra mollusks help provide more healthy environments for aquatic plants, and in some inland lakes and rivers the smallmouth bass population has increased because the additional aquatic plants have provided feeding and nursery areas for young fish. ? Envi
15、ronmental agencies, local communities, and inland lake associations are working diligently to protect people and waters from the threat of the zebra mollusks. Once the mollusks become established in bodies of water, eradication is difficult, if not impossible, because the creatures seem to be oblivi
16、ous to all but the harshest chemicalschemicals which can kill other plant and wild life. Because zebra mollusks can survive out of the water for as long as five days in cool, humid climates, boaters, fishing enthusiasts, and all lake lovers need to learn how not to transmit the invaders, in larvae a
17、nd adult form, between bodies of water. Glossaryfreighter: a large ship or airplane that is designed for carrying freight breeder: people who breed animals or plants buoy: a floating object that is used to show ships and boats where they can go and to warn them of danger(分数:42.00)(1).Based on the in
18、formation in paragraph 1, which of the following best explains the term zebra mollusks?(分数:3.00)A.small, freshwater shellfish native to North AmericaB.invasive mussels which have established themselves in inland watersC.invasive shellfish establishing themselves in salt watersD.small, freshwater mus
19、sels confined to the Balkans, Russia, and Poland(2).The word ballast in the passage is closest in meaning to(分数:3.00)A.weightedB.crushed stoneC.metal containersD.hold of a ship(3).Based upon the information in paragraph 2 and paragraph 3, what can be inferred about the mollusks mentioned in paragrap
20、h 1?(分数:3.00)A.The problems they cause can be corrected.B.Their benefits outweigh the problems they cause.C.They may be a continuing problem.D.Environmentally, they are not a problem.(4).According to paragraph 5, which is true about zebra mollusks?(分数:3.00)A.They are helpful to people.B.They only ca
21、use harm to watercraft and structures located in water.C.They like warm, dry days and cool, dry evenings.D.The threat of zebra mollusks may not be able to be eradicated.(5).In paragraph 2, the author states that the water currents(分数:3.00)A.provide an aquatic habitat for adult mollusksB.permit the y
22、oung mollusks to move easily and quickly to their new habitatsC.provide swift movement for adult mollusksD.protect boats and piers from adult mollusks(6).According to paragraph 1, what can be inferred about the spread of zebra mollusks?(分数:3.00)A.South America has been spared the infestation of zebr
23、a mollusks.B.Mollusks will continue to infest waters of the world unless eradicated.C.The mollusks discovered in Britain were canal mollusks.D.Western United States has been spared the infestation of zebra mollusks.(7).What is the problem in eradicating the zebra mollusks according to the last parag
24、raph?(分数:3.00)A.the use of chemicalsB.the ability of mollusks to live in or out of water for extended timeC.the easy transportability of mollusksD.all of the above(8).Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices c
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- 托福 分类 模拟 17 答案 解析 DOC
