题目内容
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A．The e-newspapers don"t contain pictures.
B．It only offers headlines and tops of articles.
C．Its black-and-white screen isn"t big enough.
D．The pages don"t appeal to the readers much.
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B．They are cheap and popular.
C．They are translated into English.
D．They are convenient for the users.
B．When the food colour changes.
C．When they move to different places.
D．When they are attracted by different smells.
So why is this huge increase in population taking place？ It is really due to the spread of the knowledge and practice of what is becoming known as "Death Control". You have no doubt heard of the term "Birth Control". "Death Control" is something rather different. It recognises the work of the doctors and scientists who now keep alive people who, not very long ago, would have died of a variety of then incurable diseases. Through a wide variety of technological innovations that include farming methods and the control of deadly diseases, we have found ways to reduce the rate at which we die. However, this success is the very cause of the greatest threat to mankind.
If we examine the amount of land available for this ever-increasing population, we begin to see the problem. If everyone on the planet had an equal share of land, we would each have about 50,000 square metres. This figure seems to be quite encouraging until we examine the amount of usable land we actually have. More than three-fifths of the worlds land cannot produce food.
Obviously, with so little land to support us, we should be taking great care not to reduce it further. But we are not! Instead, we are consuming its "capital" — its nonrenewable fossil fuels and other mineral deposits that took millions of years to form. but which are now being destroyed in decades. We are also doing the same with other vital resources not usually thought of as being nonrenewable such as fertile soils, groundwater and the millions of other species that share the earth with us.
It is a very common belief that the problems of the population explosion are caused mainly by poor people living in poor countries who do not know enough to limit their reproduction. This is not true. The actual number of people in an area is not as important as the effect they have on nature. Developing countries do have an effect on their environment, but it is the populations of richer countries that have a far greater impact on the earth as a whole.
According to the passage, what contributes to the population increase？
A．Human beings" ignorance.
B．The failure of "Birth Control".
C．The success of "Death Control".
D．Technological innovations.
A．Mineral resources do bring people fortune.
B．Fertile soils are nonrenewable sources in fact.
C．People have learned to use land in a protective way.
D．People usually regard groundwater as not replaceable.
B．Through a wide variety of low-frequency sounds.
C．Through their varied swimming gestures.
D．Through the echolocation.
B．Business and management.
C．Mathematics and computer science.
D．Medicines and chemistry.
More than 60,000 people have purchased the PTKs since they first become available without prescriptions last years, according to Doug Fogg, chief operating officer of Identigene, which makes the over-the-counter kits. More than two dozen companies sell DNA tests directly to the public, ranging in price from a few hundred dollars to more than $2,500.
Among the most popular: paternity and kinship testing, which adopted children can use to find their biological relatives and families can use to track down kids put up for adoption, DNA testing is also the latest rage among passionate genealogists — and supports businesses that offer to search for a familys geographic roots.
Most tests require collecting cells by webbing saliva(唾液)in the mouth and sending it to the company for testing. All tests require a potential candidate with whom to compare DNA.
But some observers are skeptical. "There is a kind of false precision being hawked by people claiming they are doing ancestry testing," says Trey Duster, a New York University sociologist. He notes that each individual has many ancestors — numbering in the hundreds just a few centuries back. Yet most ancestry testing only considers a single lineage(世系), either the Y chromosome(染色体)inherited through men in a fathers line or mitochondrial(线粒体)DNA, which is passed down only from mothers. This DNA can reveal genetic information about only one or two ancestors, even though, for example, just three generations back people also have six other great-grandparents or, four generations back, 14 other great-great-grandparents.
Critics also argue that commercial genetic testing is only as good as the reference collections to which a sample is compared. Databases used by some companies dont rely on data collected systematically but rather lump together information from different research projects. This means that a DNA database may have a lot of data from some regions and not others, so a persons test results may differ depending on the company that processes the results.
According to the passage, what is PTK used to？
A．locate one"s birth place.
B．promote genetic research.
C．find out if one is the father of a child.
D．help improve one"s intelligence.
A.makes the existing languages more resilient
B.will make it possible that English is spoken by all the people
C.undermines the progress of culture
D.puts the minority languages on the edge of extinction
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