大学英语六级考试快速阅读模拟题训练Word下载.docx

1、Y （for YES） if the statement agrees with the information given in the passage;N （for NO） if the statement contradicts the information given in the passage;NG （for NOT GIVEN） if the information is not given in the passage.For questions 5-10, complete the sentences with the information given in the pa

2、ssage.RainforestsTropical rainforests are the most diverse ecosystem（生态系统）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 planets plant and animal species.What Is a Rainforest?Generally speaking, a ra

3、inforest is an environment that receives high rainfall and is dominated by tall trees. A wide range of ecosystems fall into this category, of course. But most of the time when people talk about rainforests, they mean the tropical rainforests located near the equator.These forests receive between 160

4、 and 400 inches of rain per year. The total annual rainfall is spread pretty evenly throughout the year, and the temperature rarely dips below 60 degrees Fahrenheit.This steady climate is due to the position of rainforests on the globe. Because of the orientation of the Earths axis, the Northern and

5、 Southern hemispheres each spend part of the year tilted away from the sun. Since rainforests are at the middle of the globe, located near the equator, they are not especially affected by this change. They receive nearly the same amount of sunlight, and therefore heat, all year. Consequently, the we

6、ather in these regions remains fairly constant.The consistently wet, warm weather and ample sunlight give plant life everything it needs to thrive. Trees have the resources to grow to tremendous heights. and they live for hundreds, even thousands, of years. These giants, which reach 60 to 150 ft in

7、the air, form the basic structure of the rainforest. Their top branches spread wide in order to capture maximum sunlight. This creates a thick canopy（树冠）level at the top of the forest, with thinner greenery levels underneath. Some large trees grow so tall that they even tower overthe canopy layer.As

8、 you go lower, down into the rainforest, you find less and less greenery. The forest floor is made up of moss, fungi, and decaying plant matter that has fallen from the upper layers. The reason for this decrease in greenery is very simple：The overabundance of plants gathering sunlight at the top of

9、the forest blocks most sunlight from reaching the bottom of the forest, making it difficult for robust plants to thrive.The Forest for the TreesThe ample sunlight and extremely wet climate of many tropical areas encourage the growth of towering trees with wide canopies. This thick top layer of the r

10、ainforest dictates the lives of all other plants in the forest. New tree seedlings rarely 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.Many plant species r

11、each 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.Some plant species, called epiphytes, grow directly on the surface of the giant trees. These plants, which include a variety of orchids and

12、ferns, make up much of the under story, 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（养分）they need, which is important since they dont have access to the n

13、utrients in the ground.Stranglers 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

14、 branches extend upward, spreading 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.Competition over nutrients is almost as intense as competition for light. The excessive

15、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, rather than downward to lower levels. This makes rainforest trees somewhat unstable, since they dont have very strong

16、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 to the ground, giving the tree additional support.Rainforest trees are dependent on bacteria that are continually produci

17、ng nutrients in the ground. Rainforest bacteria and trees have a very close, symbiotic（共生的） relationship. The trees provide the bacteria with food, in the form of fallen leaves and other material, and the bacteria break this material down into the nutrients that the trees need to survive.One of the

18、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.All Creatures, Great and SmallRainforests are home

19、 to the majority of animal species in the world. And a great number of species who now live in other environments, including humans, originally inhabited the rainforests. Researchers estimate that in a large rainforest area, there may be more than 10 million different animal species.Most of these sp

20、ecies have adapted for life in the upper levels of the rainforest, where food is most 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 relationship with the plant

21、 life in a rainforest. The insects move from plant to plant, enjoying the 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.The numerous birds of the

22、 rainforest also play a major part in seed dispersal. When they eat fruit from a plant, the seeds pass through their digestive system. By the time they excrete （排泄） the seeds, the birds may have flown many miles away from the fruit-bearing tree.There are also a large number of reptiles and mammals i

23、n the rainforest. Since the weather is so hot and humid during the day, most rainforest mammals are active only at night, dusk or dawn. The many rainforest bat species are especially well adapted for this lifestyle. Using their sonar, bats navigate easily through the mass of trees in the rainforest,

24、 feeding on insects and fruit.While most rainforest species spend their lives in the trees, there is also a lot of life on the forest floor. Great apes, wild pigs, big cats and even elephants can all be found in rainforests. There are a number of people who live in the rainforests, as well. These tr

25、ibes - which, up until recently, numbered in the thousands - are being forced out of the rainforests at an alarming rate because of deforestation.DeforestationIn the past hundred years, humans have begun destroying rainforests at an alarming rate. Today, roughly 1.5 acres of rainforest are destroyed

26、 every second. People are cutting down the rainforests in pursuit of three major resources： Land for crops Lumber for paper and other wood products Land for livestock pasturesIn the current economy, people obviously have a need for all of these resources. But almost all experts agree that, over time

27、, we will suffer much more from the destruction of the rainforests than we will benefit.The worlds rainforests are an extremely valuable natural resource, to be sure, but not for their lumber or their land. They are the main cradle of life on Earth, and they hold millions of unique life forms that w

28、e have yet to discover. Destroying the rainforests is comparable to destroying an unknown planet-we have no idea what were losing. If deforestation continues at its current rate, the worlds tropical rainforests will be wiped out within 40 years.1. Virtually all plant and animal species on Earth can

29、be found in tropical rainforests.2. There is not much change in the weather in the tropical rainforests all the year round.3. The largest number of rainforests in the world are located on the African continent.4. Below the canopy level of a tropical rainforest grows an overabundance of plants.5. New

30、 tree seedlings will not survive to reach the canopy level unless _.6. Epiphytes, which form much of the under story of the rainforest, get all their water and nutrients from _.7. Stranglers are so called because they _ by blocking the sunlight and competing for the nutrients.8. Since rainforest bac

31、teria and trees depend on each other for life, the relationship they form is termed _.9. Plant species are dispersed over a large area with the help of _.10. As we are still ignorant of millions of unique life forms in the rainforest, deforestation can be compared to the destruction of _.Unit 11. N 2. Y 3. NG 4. N5. guaranteed 6. Internet access7. two customer satisfaction programs / a customer hotline and a customer call-back program8. higher prices of their pizzas9. reckless driving by the