Section BDirections: There are 2 passages in this section. Each passage is followed by som
Section B
Directions: There are 2 passages in this section. Each passage is followed by some questions or unfinished statements. For each of them there are four choices marked A, B, C and D. You should decide on the best choice.
The planet's wild creatures face a new threat—from yuppies (雅皮士), empty nesters 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 numbers of individual households has increased, because of divorce, career choice, smaller families and longer lifespan.
Jianguo Lin of Michigan State University and colleagues from Stanford University in California report in Nature, in a paper published online in advance, that a greater number of individual households, each containing on average fewer people, meant more pressure on natural resources.
Towns and cities began to sprawl (蔓生，蔓延) 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 local 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 155 million fewer households in hotspot countries in 2000.
Dr Liu's work grew from the alarming discovery that the giant pandas living in China's Wolong reserve are 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.
Only around 1.75 million species on the planet have been named and described. Biologists estimate that there could be 7 million, or even 17 million, as yet to be identified. But human numbers have grown more than sixfold in the past 200 years, and humans and their livestock are now the greatest single consumer group on the planet. The world population will continue to soar, perhaps leveling off around 9 billion in the next century. Environmental campaigners have claimed that between a quarter and a half of all the species on earth could become extinct in the next century.
Biologists report that the biodiversity is decreasing because ______.
A．more individual households are increasing greatly
B．human beings are threatening many wild creatures
C．human populations have been decreasing in recent years
D．wild creatures depend on more individual households
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