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"Files" refer to the ______ on the chessboard.
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下列关于曲面方程的结论中，错误的是( )。
In the past year, a lot has changed in the field of human spaceflight. (46) In January, President George Bush brushed aside the fact that America’s entire space-shuttle fleet was grounded when he announced grandiose plans to put people back on the moon, and then to launch a manned mission to Mars. (47) In June, Burt Rutan, an American aeronautical engineer, showed that human spaceflight was no longer the preserve of governments by sending a man to the edge of space in Space Ship One, a privately financed vehicle that cost about the same to build as a luxury yacht. That was followed in September by Sir Richard Branson, the British entrepreneur behind the Virgin brand, announcing that he had signed a deal with Mr Rutan to work on plans for a fleet of five suborbital vehicles developed from Space Ship One.(48) Now, in the dying days of the year, America’ s Congress has passed a bill that unravels a tangle about who would be responsible for regulating the fledgling industry, and under what terms. (49) The bill also allows passengers to fly on the understanding that this new generation of vehicles may not be as safe as taking a commercial flight between, say, New York and London.The official line from Virgin Galactica, as Sir Richard’ s latest venture is modestly named, is that this coming change in the law makes no practical difference to the firm’s plans, since they do not intend to fly unless they can make their spacecraft as safe as a private jet. But it must surely come as some sort of relief. In any case, Will Whitehorn, director of corporate affairs at Virgin’ s headquarters in London, and soon to become the president of Virgin Galactica, says that work is under way on a mock-up of the interior of a new spacecraft that will hold five passengers. (50) Virgin has already committed $ 20m towards licensing the SpaceShipOne technology from Mr Rutan and his financial backer Paul Allen, a software billionaire. Virgin has already committed $ 20m towards licensing the SpaceShipOne technology from Mr Rutan and his financial backer Paul Allen, a software billionaire.
Which of the following statement about Knights is Not true
TEXT E In the 1960s scientists begin to recognize that environmental contaminants could not only affect the health and survival of individual animals but also alter the prospects for their off-spring and thereby potentially change the genetic makeup of entire populations. Researchers were first altered to problems in wildlife in the 40s after the populations of eagles, falcons, and the other fish-eating birds in Britain plummeted. In nest after nest the birds’ eggshells were so thin that they cracked under the weight of the adults during incubation. In the 1960s David Peakall and other wildlife toxicologists demonstrated that the accumulation of very high levels of such pesticides as DDT in the birds’ tissues had seriously impaired their productive capabilities. Some of these declines resulted in the complete disappearance of populations from large portions of their former range. In North America, for example, the eastern population of the peregrine falcon was virtually wiped out. More recently, the Golf Coast population of the brown pelican disappeared as a result of eggshell thinning thought to be caused by the organochlorine pesticides dieldrin and endrin. Since then, researchers have provided additional evidence that environmental pollution can affect future generations. For example, exposure to high levels of PCBs has been shown to affect the learning and behavior of children. In the 1980s Snadra W. Jacobson and Joseph L. Jacobson of Wayne State University, Detroit, Michigan, studied a group of children whose mothers had eaten PCB—contained fish from Lake Michigan. The researchers found that the children’s prenatal exposure to these compounds resulted in neurological anomalies at birth and developmental delays in motor function during infancy. The Jacobson retested the children at age 11. In a 1996 report they noted that the children exhibited significantly poorer intellectual function, amounting to a 6.2 point deficit in the IQs of the most highly exposed subjects. Contaminants also have been linked to a critical loss of genetic variability in populations of living organisms. One of the best studies of this phenomenon was published in 1994 by M. H Murdoch and P.D.N. Hebert of the University of Guelph, Ontario. The study measured the variations in the mitochondrial DNA (mtDNA) of populations of brown bullhead catfish in the Great Lakes, comparing bullheads from pristine reference areas with bullheads living in heavily contaminated with such pollutants as organochlorines and petrochemicals. The two researchers used one of the most powerful tools of modern molecular population genetics-molecular analysis of DNA. By revealing differences in the specific code, i.e., in the sequence of nucleotides, contained in the DNA of a particular gene, the technique can help identify and quantify genetic variety within and among populations. For their study, Murdoch and Hebert examinated variations in genes of the cellular mitochondria, which possess their own DNA (mtDNA) that is distinct from the DNA found in the cell nucleus. Because mitochondrial genes are not "shuffled" in the production of sperm and egg cells, as are nuclear genes, and because they are transmitted to offspring only by the mother, they are ideal for charting the relatedness and evolutionary history of spaces. The researchers found that although the numbers of fish were abundant in both types of sites, the levels of genetic variability were always significantly higher in the pristine areas. The most likely explanation is that bullheads populations in polluted waters crashed after their initial contact with contaminants, but the remaining fish were able to repopulate because a few individuals possessed rare genes that allowed them to adapt and survive. Thus, even though the bullhead populations appeared to be thriving in contaminated areas, the genetic makeup of their populations had undergone a damaging simplification, a depletion of the storehouse of adaptations that animals can draw upon to surmount environmental challenges such as the introduction of a new disease of fluctuations in climate. Their genetic diversity potentially could be quickly increased by the influx of new genes from migrant fish, but most fish from other populations might survive in the polluted sites long enough to contribute to the gene pool. From the passage, we know that dieldrin is ______.
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