成本递减行业（Decreasing-cost industry）

规模收益递减（ Decreasing return to scale）

Text 1
The planet’s wild creatures face a new threat from yuppies, empty nesters, singletons and one parent families. Biologists studying the pressure on the planet’s dwindling biodiversity today report on a new reason for alarm. Although the rate of growth in the human population is decreasing, the number of individual households is exploding. Even where populations have actually dwindled—in some regions of New Zealand, for instance—the number of individual households has increased, because of divorce, career choice, smaller families and longer lifespans.
Jianguo Liu of Michigan State University and colleagues from Stanford University in California re port in Nature, in a paper published online in advance, that a greater number of individual house holds, each containing on average fewer people, meant more pressure on natural resources. Towns and cities began to sprawl as new homes were built. Each household needed fuel to heat and light it; each household required its own plumbing, cooking and refrigeration. "In larger households, the efficiency of resource consumption will be a lot higher, because more people share things," Dr. Liu said. He and his colleagues looked at the population patterns of life in 141 countries, including 76 "hotspot" regions unusually rich in a variety of endemic wildlife. These hot spots included Australia, New Zealand, the US, Brazil, China, India, Kenya, and Italy. They found that between 1985 and 2000 in the "hotspot" parts of the globe, the annual 3.1% growth rate in the number of households was far higher than the population growth rate of 1.8 %.
"Had the average household size remained at the 1985 level," the scientists report, "there would have been 155m fewer households in hotspot countries in 2000. Paradoxically, smaller households do not mean smaller homes. In Indian River county, Florida, the average area of a one-storey, single family house increased 33 % in the past three decades."
Dr. Liu’s work grew from the alarming discovery that the giant pandas living in China’s Wolong reserve were more at risk now than they were when the reserve was first established. The local population had grown, but the total number of homes had increased more swiftly, to make greater inroads into the bamboo forests.
Gretchen Daily of Stanford, one of the authors, said: "We all depend on open space and wild places, not just for peace of mind but for vital services such as crop pollination, water purification and climate stabilization. The alarming thing about this study is the finding that, if family groups continue to become smaller and smaller, we might continue losing biodiversity—even if we get the aggregate human population size stabilised."

The first paragraph mainly tells us that（）

A:the amount of wildlife is diminishing. B:the population of human is decreasing. C:New Zealanders live an unstable life. D:the structure of families is changing.

Africa’s elephants are divided between the savannahs of eastern and southern Africa and the forests of central Africa. Some biologists reckon the forest ones-smaller, with shorter, straighter tusks-may even constitute a distinct species. But not for long, at the latest rate of poaching. The high price of ivory is increasing the incentive to kill elephants everywhere in Africa, and especially in places where there is virtually no law.
The latest reports suggest that the forest elephant population is collapsing on the back of rising Chinese demand for ivory. Some conservationists argue that a recent decision by the Convention on International Trade in Endangered Species (CITES) to auction 108 tonnes of stockpiled ivory from southern Africa may be prompting more poaching in central and eastern Africa, as criminals seek to mix illicit ivory in with the legitimate kind. But some economists maintain that the legitimate sale of ivory lowers prices, thus decreasing the incentive to poach. A study of a previous sale of ivory suggested it did not lead to more intensive poaching.
Either way, the Congo basin is " hemorrhaging elephants ", says TRAFFIC, which monitors trade in wildlife. The head of the 790,000-hectare (1,952,000-acre) Virunga National Park in eastern Congo, Emmanuel de Merode, reports that 24 elephants have been poached in his park so far this year. The situation is dire: 2,900 elephants roamed Virunga when Congo became independent in 1964,400 in 2006, and fewer than 200 today. Most have been poached by militias, particularly Hutu rebels from Rwanda who hack off the ivory and sell it to middlemen in Kinshasa, Congo’s capital, who then smuggle it to China.
Once ivory has left its country of origin, and if it is not seized by customs officials, it can be hard to identify its source and those responsible for acquiring it. But forensic help may be at hand. Scientists from the University of Washington are using genetic markers in elephant dung to identify exactly where ivory has been poached. This should help governments in countries such as Tanzania and Zambia, which are capable of catching poachers, but not in anarchic eastern Congo, where 120-odd rangers have been killed in Virunga in recent years trying to protect elephants and gorillas.
With an influx of businessmen and other officials from China engaged in infrastructure projects such as road building and logging, the slaughter is expected to accelerate. Forest elephants may survive in large numbers only in remote protected pockets of the Congo basin, such as the Odzala-Koukoua National Park in Congo-Brazzaville and Minkebe National Park in northeast Gabon.
According to the text, what is the intention of the Convention on International Trade in Endangered Species (CITES) to auction the stockpiled ivory

A:To get income for the convention. B:To lower the price of ivory, thus decreasing the incentive to poach. C:To dispose of the customs seized ivory. D:To open the market of legitimate vendition of ivory.

Section Ⅱ Reading Comprehension Part A Directions: Read the following four texts. Answer the questions below each text by choosing A, B, C or D. Mark your answers on ANSWER SHEET 1. Text 1 The planet’s wild creatures face a new threat from yuppies, empty nesters, singletons and one parent families. Biologists studying the pressure on the planet’s dwindling biodiversity today report on a new reason for alarm. Although the rate of growth in the human population is decreasing, the number of individual households is exploding. Even where populations have actually dwindled—in some regions of New Zealand, for instance—the number of individual households has increased, because of divorce, career choice, smaller families and longer lifespans. Jianguo Liu of Michigan State University and colleagues from Stanford University in California re port in Nature, in a paper published online in advance, that a greater number of individual house holds, each containing on average fewer people, meant more pressure on natural resources. Towns and cities began to sprawl as new homes were built. Each household needed fuel to heat and light it; each household required its own plumbing, cooking and refrigeration. "In larger households, the efficiency of resource consumption will be a lot higher, because more people share things," Dr. Liu said. He and his colleagues looked at the population patterns of life in 141 countries, including 76 "hotspot" regions unusually rich in a variety of endemic wildlife. These hot spots included Australia, New Zealand, the US, Brazil, China, India, Kenya, and Italy. They found that between 1985 and 2000 in the "hotspot" parts of the globe, the annual 3.1% growth rate in the number of households was far higher than the population growth rate of 1.8 %. "Had the average household size remained at the 1985 level," the scientists report, "there would have been 155m fewer households in hotspot countries in 2000. Paradoxically, smaller households do not mean smaller homes. In Indian River county, Florida, the average area of a one-storey, single family house increased 33 % in the past three decades." Dr. Liu’s work grew from the alarming discovery that the giant pandas living in China’s Wolong reserve were more at risk now than they were when the reserve was first established. The local population had grown, but the total number of homes had increased more swiftly, to make greater inroads into the bamboo forests. Gretchen Daily of Stanford, one of the authors, said: "We all depend on open space and wild places, not just for peace of mind but for vital services such as crop pollination, water purification and climate stabilization. The alarming thing about this study is the finding that, if family groups continue to become smaller and smaller, we might continue losing biodiversity—even if we get the aggregate human population size stabilised."

The first paragraph mainly tells us that（）

A:the amount of wildlife is diminishing. B:the population of human is decreasing. C:New Zealanders live an unstable life. D:the structure of families is changing.

The planet’s wild creatures face a new threat -- from yuppies, empty nesters, singletons and one parent families. Biologists studying the pressure on the planet’s dwindling biodiversity today report on a new reason for alarm. Although the rate of growth in the human population is decreasing, the number of individual households is exploding. Even where populations have actually dwindled -- in some regions of New Zealand, for instance -- the number of individual households has increased, bemuse of divorce, career choice, smaller families and longer lifespans.
Jianguo Liu of Michigan State University and colleagues from Stanford University in California re- port in Nature, in a paper published online in advance, that a greater number of individual house-holds, each containing on average fewer people, meant more pressure on natural resources. Towns and cities began to sprawl as new homes were built. Each household needed fuel to heat and light it; each household required its own plumbing, cooking and refrigeration. "In larger households, the efficiency of resource consumption will be a lot higher, because more people share things," Dr. Liu said. He and his colleagues looked at the population patterns of life in 141 countries, including 76 "hotspot" regions unusually rich in a variety of endemic wildlife. These hot spots included Australia, New Zealand, the US, Brazil, China, India, Kenya, and Italy. They found that between 1985 and 2000 in the "hotspot" parts of the globe, the annual 3.1% growth rate in the number of households was far higher than the population growth rate of 1.8%.
"Had the average household’ size remained at the 1985 level," the scientists report, "there would have been 155m fewer households in hotspot countries in 2000. Paradoxically, smaller households do not mean smaller homes. In Indian River county, Florida, the average area of a one-storey, single family house increased 33 % in the past three decades."
Dr. Liu’s work grew from the alarming discovery that the giant pandas living in China’s Wolong reserve were more at risk now than they were when the reserve was first established. The local population had grown, but the total number of homes had increased more swiftly, to make greater inroads into the bamboo forests.
Gretchen Daily of Stanford, one of the authors, said: "We all depend on open space and wild places, not just for peace of mind but for vital services such as crop pollination, water purification and climate stabilization. The alarming thing about this study is the finding that, if family groups continue to become smaller and smaller, we might continue losing biodiversity -- even if we get the aggregate human population size stabilised."

The first paragraph mainly tells us that（）

A:the amount of wildlife is diminishing. B:the population of human is decreasing. C:New Zealanders live an unstable life. D:the structure of families is changing.

Text 3

According to the text, what is the intention of the Convention on International Trade in Endangered Species (CITES) to auction the stockpiled ivory

A:To get income for the convention. B:To lower the price of ivory, thus decreasing the incentive to poach. C:To dispose of the customs seized ivory. D:To open the market of legitimate vendition of ivory.