大学英语四级综合-37及答案解析.doc

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1、大学英语四级综合-37 及答案解析(总分：450.00，做题时间：90 分钟)一、Reading Comprehensio(总题数：5，分数：450.00)Passage SixRainforestsTropical rainforests are the most diverse ecosystem on Earth, and also the oldest. Today, tropical rainforests cover only 6 percent of the Earths ground surface, but they are home to over half of the

2、planets plant and animal species. In this completely unique world, there are thousands of species we have yet to discover.In this article, well travel into the tropical rainforest to see what makes it such a beautiful environment for plants and animals. Well also see why the rainforests are in dange

3、r and look at some of the ways this affects us.What Is a Rainforest?Generally speaking, a rainforest is an environment that receives high rainfall and is dominated by tall trees. A wide range of ecosystems fall into this category, of course, including the old-growth temperate forests of the Pacific

4、Northwest. But most of the time when people talk about rainforests, they mean the tropical rainforests located near the equator.These forests, concentrated in Africa, Australia, Asia, and Central and South America, receive between 160 and 400 inches (406.4 to 1016 cm) of rain per year. Unlike the ra

5、inforests farther to the north and south, tropical rainforests dont really have a “dry season“. In fact, they dont have distinct seasons at all. The total annual rainfall is spread pretty evenly throughout the year, and the temperature rarely dips below 60 degrees Fahrenheit ( 16 degrees Celsius).Th

6、e Forest for the TreesWe saw in the last section that the ample sunlight and extremely wet climate of many tropical areas encourage the growth of towering trees with wide canopies (遮篷). This thick top layer of the rainforest dictates the lives of all other plants in the forest. New tree seedlings ra

7、rely survive to make it to the top unless some older trees die, creating a “hole“ in the canopy. When this happens, all of the seedlings on the ground level compete intensely to reach the sunlight. Most other plants survive by taking advantage of the trees that form the canopy layer.Many plant speci

8、es reach the top of the forest by climbing the tall trees. It is much easier to ascend this way, because the plant doesnt have to form its own supporting structure. Lianas, long, woody plants that can grow more than 8 inches (20 cm) across, will often climb tall trees all the way up to the canopy la

9、yer. At the top of the forest, these climbers may spread from tree to tree, making the canopy ceiling even thicker.Some plant species, called epiphytes (附生植物), grow directly on the surface of the giant trees. These plants, which include a variety of orchids and ferns, make up much of the understory

10、(下层矮生植被), the layer of the rainforest right below the canopy. Epiphytes are close enough to the top to receive adequate light, and the runoff from the canopy layer provides all the water and nutrients they need, which is important since they dont have access to the nutrients in the ground.Stranglers

11、 and ButtressesSome epiphytes eventually develop into stranglers. They grow long, thick roots that extend down the tree trunk into the ground. As they continue to grow, the roots form a sort of web structure all around the tree. At the same time, the strangler plants branches extend upward, spreadin

12、g out into the canopy. Eventually, the strangler may block so much light from above, and absorb such a high percentage of nutrients from the ground below, that the host tree dies. When the host decomposes, the stranglers lattice of roots remains, giving the plant the structure it needs to reach from

13、 the forest floor to the canopy.Competition over nutrients is almost as intense as competition for light. The excessive rainfall rapidly dissolves nutrients in the soil, making it relatively infertile except at the top layers. For this reason, rainforest tree roots grow outward to cover a wider area

14、, rather than downward to lower levels. This makes rainforest trees somewhat unstable, since they dont have very strong anchors in the ground. Some trees compensate for this by growing natural buttresses. These buttresses are basically tree trunks that extend out from the side of the tree and down t

15、o the ground, giving the tree additional support.Rainforest trees are dependent on bacteria that are continually producing nutrients in the ground. Rainforest bacteria and trees have a very close, symbiotic relationship. The trees provide the bacteria with food, in the form of fallen leaves and othe

16、r material, and the bacteria break this material down into the nutrients that the trees need to survive. Even with this amazing symbiotic cycle, nutrients are scarce. Some plant species gather additional nutrients by capturing bugs or catching plant material that falls from the canopy above.One of t

17、he most remarkable things about rainforest plant life is its diversity. The temperate rainforests of the Pacific Northwest are mainly composed of a dozen or so tree species. A tropical rainforest, on the other hand, might have 300 distinct tree species. This plant life is spread out over wide areas-

18、in a square acre, an entire species might be represented by only a few individual plants. As well see in the next section, rainforest animal life is similarly diverse.All Creatures, Great and SmallRainforests are home to the majority of animal species in the world. And a great number of species who

19、now live in other environments, including humans, originally inhabited the rainforests. Researchers estimate that in a large rainforest area, there may be more than l 0 million different animal species.Most of these species have adapted for life in the upper levels of the rainforest, where food is m

20、ost plentiful. Insects, which can easily climb or fly from tree to tree, make up the largest group ( ants are the most abundant animal in the rainforest). Insect species have a highly symbiotic (共生的) relationship with the plant life in a rainforest. The insects move from plant to plant, enjoying the

21、 wealth of food provided there. As they travel, the insects may pick up the plants seeds, dropping them some distance away. This helps to disperse the population of the plant species over a larger area-underneath the canopy, the wind is not strong enough to carry seeds a significant distance, so pla

22、nts depend entirely on animals for seed dispersal. Less harmful insects may also help a plant by fighting off more destructive insect species.The numerous birds of the rainforest also play a major part in seed dispersal. When they eat fruit from a plant, the seeds pass through their digestive system

23、. By the time they excrete the seeds, the birds may have flown many miles away from the fruitbearing tree.（分数：90.00）(1).Tropical rainforests cover only 6% of the Earths land, but are home to over half of all the species, which indicates that _（分数：9.00）A.we are familiar with themB.no more species of

24、rainforests need to be discoveredC.most species will not survive without tropical rainforests on EarthD.tropical rainforests are the oldest and the most diverse ecosystem(2).Generally speaking, a rainforest is considered as an environment _（分数：9.00）A.with a high capacity of species and has distinct

25、seasonsB.which does not include the old-growth temperate forestsC.receiving little rainfall since located in the tropicsD.featured by tall trees with high rainfall(3).When we mention rainforests, what will usually occur to our minds?（分数：9.00）A.Forests concentrated mostly in Asia.B.The old-growth tem

26、perate forests.C.Rainforests farther to the north and south.D.The tropical rainforests located near the equator.(4).About rainforests, which statement is obviously NOT reasonable?（分数：9.00）A.Rainforests locate near equator with relatively temperate temperature.B.Rainfall spread evenly with no distinc

27、t seasons.C.Rainforests are dominated by tall trees with diverse animal life.D.Without rainforest, all the life on the earth will di(5).It is much easier for many plant species to reach the top of the forest by _（分数：9.00）A.forming the canopy layerB.climbing the tall treesC.making up the understoryD.

28、growing directly on the surface of the giant trees(6).Which of the following is NOT the result of the intense competition for nutrients?（分数：9.00）A.Rainforest tree roots grow very deep.B.Rainforest tree roots grow outward.C.Rainforest trees are somewhat unstable.D.Rainforest trees dont have strong an

29、chors in the groun(7).Which of the following can illustrate the remarkable diversity of rainforest plant life?（分数：9.00）A.The number of plant species of a tropical rainforest is a little more than that of the temperate rainforests.B.A tropical rainforest has about 200 distinct tree species.C.The plan

30、t life is spread out over wide areas.D.The plant life is scarce since the rainforest is dominated by tall trees.(8).Rainforests accommodate the majority of _ in the world.（分数：9.00）填空项 1:_(9).The most animals the rainforests abound in are_（分数：9.00）填空项 1:_(10).Plants depend entirely on animals for_（分数

31、：9.00）填空项 1:_Passage SevenNew YorkFor most of us, the word vacation conjures up images of lounging on a Caribbean beach or touring the picturesque terrain of some European country. An urban center (like New York City) bustling with people, traffic and skyscrapers might not immediately come to mind.

32、However, large cities often offer tourists an incredible variety of sites and activities. The City, as New York City is often referred to, is home to world-renowned museums and restaurants, exciting attractions, an array of entertainment and unbeatable shopping. If you are anything like the 29 milli

33、on American travelers that visit “the Big Apple“ annually, your next vacation spot just may be New York City.As a travel destination, New York has something to offer almost every visitor. Though tourism has dropped since September 11, 2001, there are still lots of reasons to visit what many consider

34、 the greatest city in the world.In this article, we will explore the basics of what every visitor needs to know before planning a trip to New York City. You will leam about getting to and around the city, the neighborhoods, some main (and lesser known) attractions and some pretty useful secrets.City

35、 OverviewNew York City (NYC) is located on the Eastern Atlantic coast of the United States. It rests at the mouth oftbe Hudson River. The city is often referred to as a “city of islands“. Greater NYC is made up of five distinct areas called boroughs. These boroughs include Manhattan, Brooklyn, Queen

36、s, Staten Island and the Bronx. The boroughs are separated from each other by various bodies of water and are connected by subways, bridges and tunnels.In terms of the geography of NYC, it is best to imagine the Greater New York area as a main center island (Manhattan) surrounded by outer islands (t

37、he other boroughs): Queens is located just east of Manhattan. Brooklyn is situated to the southeast of Manhattan. Staten Island is located southwest of Manhattan. The Bronx is located north of Manhattan.Only Manhattan and Staten Island are on their own land masses. The Bronx is the only borough that

38、 is attached to the New York State mainland.When people refer to New York City, they are usually talking about Manhattan. Most of NYCs main attractions are located in this borough and the majority of visitors spend most of their vacation here. For this reason, lets examine the organization of the is

39、land of Manhattan.A Short History of the Big AppleNo discussion about New York would be complete without asking why New York is referred to as “the Big Apple“. Like many things about New York, youll probably get a different answer depending on who you ask. According to the Museum of the City of New

40、York, it is believed that in the 1920s, a sportswriter overheard stable hands in New Orleans refer to New York Citys racetracks as “the Big Apple“. The phrase was most widely used by jazz musicians during the 1930s and 40s. They adopted the term to refer to New York City, and especially Harlem, as t

41、he jazz capital of the world.The Italian navigator Giovanni da Verrazano may have been the first European to explore the New York region in 1524. More than 80 years later, Englishman Henry Hudson sailed up the river that now bears his name. But it was Dutch settlements that truly started the city. I

42、n 1624, the town of New Amsterdam was established on lower Manhattan. Two years later, according to local legend, Dutchman Peter Minuit purchased the island of Manhattan from the local Native Americans for 60 guilders (about $24) worth of goods.Few people realize that New York was briefly the U.S. c

43、apital from 1789 to 1790 and was the capital of New York State until 1797. By 1790, it was the largest U.S. city. In 1825, the opening of the Erie Canal, which linked New York with the Great Lakes, led to continued expansion.A charter was adopted in 1898 incorporating all five boroughs into Greater

44、New York. New York has always been and remains a city of immigrants. Patterns of immigration are integral to the citys history and landscape, hnmigration, mainly from Europe, swelled the citys population in the late 19th and early 20th centuries. After World War , many African-Americans from the Sou

45、th, Puerto Ricans, and Latin Americans migrated to the city.as well. Because of the variety of innnigrant groups, both historically and currently, New York is often referred to as a true “melting pot“.Getting to New York CityThere are several important things to think about when traveling to New Yor

46、k. If youre thinking about driving into the city, consider this: Tolls for turnpikes (收费公路), bridges and tunnels are the highest in the nation. Traffic, especially on weekdays, can be extremely heavy. Finding a parking space is a rarity and parking can cost five times what it costs anywhere else.Tra

47、ins and buses can be good alternatives to driving into New York. Amtrak trains arrive in New Yorks Penn Station (32nd Street and 7th Avenue) from all over the country. All major bus lines, including Greyhound, also serve the New York area. Buses usually arrive at the Port Authority Bus Terminal (42n

48、d Street and 8th Avenue).If you are like most travelers to New York, you will probably make your way through one of the areas three airports. La Guardia, John F. Kennedy and Newark Airport all serve the area. La Guardia is the closest airport to the city-only 8 miles east of Manhattan in Queens. Mos

49、t United States domestic flights enter and exit through this airport. International flights often go through John F. Kennedy Airport (also known as JFK), which is about 15 miles east of the city. Newark Airport is located in New Jersey, but is no farther from Manhattan (about 15 miles) than JFK. Transportation into Manhattan once you arrive at any of the airports is pretty simple, but can be time consuming depending on traffic. Assume it will take from thirty minutes up to an hou