题目内容
（请给出正确答案）
Most rainforest soils are thin and poor because （）．
A．the composition of the topsoil is rather unstable
B．black carbon is washed away by heavy rains
C．organic matter is quickly lost due to heat and rain
D．long-term farming has exhausted the ingredients essential to plant growth
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更多“Most rainforest soils are thin…”相关的问题
The area deforested in the past year was up 6% in 2003, far worse than the Brazilian government's predictions that it would rise by no more than about 2%. It was the second worst year for the destruction of the rainforest since satellite surveys began. It is reckoned that almost a fifth of the Brazilian part of the forest has now been wiped outs if it were to continue at this rate, it would all be flattened within the next two centuries. Things are hardly any better in those portions of Amazonia that lie in neighboring countries: Ecuador has lost about half of its forest, mainly due to illegal logging, in the past 30 years. Worse still, tropical forests have been disappearing at an even faster rate elsewhere in the world, such as in Africa. The world's greatest stores of biodiversity—and some of its main suppliers of the oxygen we breathe—are still being chewed up at an alarming rate, despite decades of talk among world leaders and environmentalists about the need to preserve them.
As has been seen before in Brazil, the surge in the rate of deforestation is a sign that the country's economy is booming—recently it bas been growing at an annual rate of around 5%. Most of the timber felled illegally in Amazonia is sold to domestic buyers, in particular to the construction industry in Brazil's richer southern states. But the forest is also threatened by the rapid expansion of farming and ranching. In the past year, almost half of the total deforestation was in the state of Mato Grosso on the forest's southern part, where huge areas have been flattened to grow soybeans. Last year Brazil earned about $10 billion from exporting soy products, exceeding its income from coffee' and sugar, the country's traditional export crops. Mato Grosso's governor, Blairo Maggi, is also its soybean king—his family's farms are' the world's largest single producer of the crop.
The rate at which the forest is being flattened could easily rise further. To boost the region's economic development and make attack on poverty, the government plans to asphalt(铺设沥青) and widen the BR-163 highway that slices the forest roughly in half, running from north to south. Though the government has been working with environmental groups and others to try to limit the scheme's impact, past experience has shown that improved road access invariably means more intrusion of the forest by loggers, ranchers, farmers, mineral prospectors and others.
For much of Brazil's recent history, in particular during the country's 1964-85 military dictatorship, successive governments were obsessed(困扰) with populating and "developing" Amazonia, convinced that otherwise a foreign power might seize it. Large sums were spent building highways to open up the forest and a lot of subsidies were offered to get people to resettle there. However, the huge area of abandoned former forest land alongside previous road schemes show that, in fact, much of the region lacks suitable soil and climate for agriculture.
More recent governments have taken the axe to the worse schemes that encouraged people to destroy the rainforest. Besides Brazil's tough conservation laws, there are now countl
A．Y
B．N
C．NG
Rain forests
Tropical 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 Earth's ground surface, but they are home to over half of the planet’s plant and animal species.
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. But most of the time when people talk about rainforests, they mean the tropical rainforests located near the equator.
These forests receive between 160 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 Earth's axis, the Northern and 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 arc not especially affected by this change. They receive nearly the same amount of sunlight, and therefore heat, all year. Consequently, the weather 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 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 over the canopy layer.
As 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 the forest blocks most sunlight from reaching the bottom of the forest, making it difficult for robust plants to thrive.
The Forest for the Trees
The 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 rainforest 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 reach the top of the forest by climbing the tall trees. It is much easier to ascend this way, because the plant doesn't 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 ferns, make up much of the understory, 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 don't have access to the nutrients in the ground.
Stranglers and Buttresses
Some 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 plant's 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.
&
A．Y
B．N
C．NG
Rainforests
Tropical 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 Earth's ground surface, but they are home to over half of the planet's plant and animal species.
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. But most of the time when people talk about rainforests, they mean the tropical rainforests located near the equator.
These forests receive between 160 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 Earth's axis, the Northern and 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 weather 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 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 over the canopy layer. As 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 the forest blocks most sunlight from reaching the bottom of the forest, making it difficult for robust plants to thrive.
The Forest for the Trees
The 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 rainforest 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 cane by. When this happens, all of the seedlings on the ground level compete intensely to reach the sunlight.
Many plant species reach the top of the forest by climbing the tall trees. It is much easier to ascend this way, because the plant doesn't 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 ferns, make up much of the under story, the layer of the rain forest fight 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 don't have access to the nutrients in the ground.
Stranglers and Buttresses
Some 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 plant's 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
A．Y
B．N
C．NG
听力原文： [32] New England is an area of mountains, valleys, and rivers. It is said that in New England [32] one is always climbing hills. A large part of New England is also made up of farms and farming lands. Yet New Eng land is not really a fanning area. The farms are small. Generally they are only large enough to support one family. It also happens that the soil of New England is not good. [33] This soil has been worked and planted for so many years that it has lost its value.
[34] Most New Englanders today work in factories or small businesses. In these factories they make watches and clocks, shoes, clothing, special tools for industry, leather goods, etc. New England workmen are famous for their skill in making many of these things. [35] This skill is often passed down in families from father to son.
(33)
A．It is completely flat.
B．It has few rivers.
C．It has many large lakes.
D．It is hilly.
听力原文： Today, I'd like to talk about some of the changes land can undergo, specifically desertification. That's the process through which land becomes part of a desert. Now a desert is defined as a place that receives a certain maximum amount of rainfall. But you may not know that it usually takes more than just a lack of water to turn productive land into a desert. There are several specific human activities that when combined with a lack of rainfall encourage desertification. For example, over-cultivation, growing more crops than soil can support. The soil loses its nutrients, so it needs either to be fertilized or to be left unused for at least a season. But if neither of these things happens, if these nutrients in the soil don't get replaced, the damaged soil stops producing. Another cause of desertification is overgrazing. That's when the grasses and trees and shrubs of an area are expected to feed more animals than they reasonably can. Too many animals eating in the same area will kill the vegetation. And it's because it's the roots of this vegetation that hold much of the soil together, when too much of the vegetation dies, the soil corrodes. But maybe the most paradoxical example of human behavior. that can lead to desertification is irrigation. It may seem to run counter to common sense to say that introducing water into an area can cause it to become more like a desert. But there are plenty of bad irrigation practices that do just that. Bringing in too much salty water and then not providing adequate drainage for it will till the soil with salt, and turn the area into a desert.
(30)
A．It receives more nutrients than it can absorb.
B．It becomes oversaturated with water.
C．It loses the ability to support insect life.
D．It loses nutrients that aren't replaced.
1.This passage is most probably written as ____.
A、the beginning part of a certain chapter
B、the middle part of a certain chapter
C、the last part of a certain chapter
D、a self-contained chapter
2.Which of the following topics is NOT discussed in the passage？ ____
A、Natural Resources
B、Industrial Pollution
C、Unemployment
D、Overpopulation
3.The author's purpose in the first paragraph is to tell us the fact that ____.
A、deserts are hostile
B、Antarctic is very cold
C、human beings now inhabit the entire Earth
D、there are many different species on planet Earth
4.According to the passage, some natural resources like fuels and metals ____.
A、are no longer new
B、will never be gone
C、will soon be used up
D、can not be used at present
5.The phrase `strive for' in the second paragraph means ____.
A、fight with each other in order to get'
B、make great efforts to achieve'
C、have a violent struggle because of'
D、suffer a lot from'
6.Which pollution is NOT mentioned in the passage？ ____
A、Air Pollution
B、Water Pollution
C、Soil Pollution
D、Sound Pollution
听力原文： The agricultural revolution in the 19th century involved two things: the invention of labor-saving machinery and the development of scientific agriculture. Labor-saving machinery naturally appeared first where labor was scarce. "In Europe." said Thomas Jefferson, "the object is to make the most of their land, labor being rich enough; here it is to make the most of our labor, land being rich enough." It was in the United States, therefore, that the great advances in nineteenth-century agricultural machinery first came.
At the opening of the century, with the exception of crude equipment, farmers could have carried practically all of the existing agricultural implements on their backs; by 1860, most of the machinery in use today had been designed in an early form. The most important of the inventions was the iron plow. As early as 1790 Charles Newbold of New Jersey had been working on the idea of a cast-iron plow andspent his entire fortune in introducing his invention. The farmers, however, were not interested in it, believing that the iron poisoned the soil and made the weeds row. Nevertheless, many people devoted their attention to the plow, until in 1869 James Oliver of South Bend, Indiana turned out the first steel plow.
(33)
A．The invention of machine that can save labor and the progress of scientific agriculture.
B．The invention of crude equipments and agricultural implements.
C．The advance of agriculture machinery and the iron plow.
D．The idea of a cast-iron plow and steel plow.
Fifty years ago nature study was not part of the school work; scientific forestry was a new idea; timber was still cheap because it could be brought in any quantity from distant woodlands; soil destruction and river floods were not national problems; nobody had yet studied long-terms climatic cycles in relation to proper land use; even the word “conservation” had nothing of the meaning that it has for us today.
For the sake of ourselves and those who will come after us, we must now set about repairing the mistakes of our forefathers. Conservation should, therefore, be made a part of everyone’s daily life. To know about the water table (水位) in the ground is just as important to us as a knowledge of the basic arithmetic formulas. We need to know why all watersheds (上游源头森林地带集水区) need the protection of plant life and why the running current of streams and rivers must be made to yield their full benefit to the soil before they finally escape to the sea. We need to be taught the duty of planting trees as well as of cutting them. We need to know the importance of big, mature trees, because living space for most of man’s fellow creatures on this planet is figured not only in square measure of surface but also in cubic volume above the earth. In brief, it should be our goal to restore as much of the original beauty of nature as we can.
第26题：The author’s attitude towards the current situation in the exploitation of natural resources is ________.
A) positive
B) neutral
C) suspicious
D) critical
A．it does no harm to the topsoil of the rainforest
B．it destroys rainforest soils
C．it helps improve rainforest soils
D．it diminishes the organic matter in rainforest soils
Below the canopy level of a tropical rainforest grows an overabundance of plants.
A．Y
B．N
C．NG
