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OG12 OG15 OG16 OG17 GWD PREP08 Test 2 OG18 OG19 OG20 OG2022
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Rock samples taken from the remains of an asteroid about twice the size of the 6-mile-wide asteroid that eradicated the dinosaurs has been dated to be 3.47 billion years old and thus is evidence of the earliest known asteroid impact on Earth.
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300难题 OG17
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It may someday be worthwhile to try to recover uranium from seawater, but at present this process is prohibitively expensive.
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300难题 OG17
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To read of Abigail Adams' lengthy separation from her family, her difficult travels, and her constant battles with illness is to feel intensely how harsh life was even for the so-called aristocracy of Revolutionary times.
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300难题 OG17
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A study of children of divorced parents found that ten years after the parents' divorce, children who had been under six years of age at the time of the settlement were not preoccupied, nor even very curious, about the reasons that led to their parents' divorces.
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300难题 OG17
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Many states, in search of industries that are clean, fast-growing, and pay good wages to skilled workers, are trying to attract high-technology industries.
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300难题 OG17
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The newspaper story accurately recounted the history of the colonial mansion, that it contained thirteen rooms, and that it had a reputation for being a haunted house.
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300难题 OG17
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The use of gravity waves, which do not interact with matter in the way electromagnetic waves do, hopefully will enable astronomers to study the actual formation of black holes and neutron stars.
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300难题 OG17
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Carbon-14 dating reveals that the megalithic monuments in Brittany are nearly 2,000 years as old as any of their supposed Mediterranean predecessors.
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300难题 OG17
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Financial uncertainties from the accident at Three Mile Island may prove even more deterring to the nuclear industry than political opposition is.
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300难题 OG17
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Since the 1930s aircraft manufacturers have tried to build airplanes with frictionless wings, shaped so smoothly and perfectly that the air passing over them would not become turbulent.
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300难题 OG17
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An archaeological excavation at what might have been a workshop where statues were reproduced yielded 1,532 fragments of human figures, including 7 intact statues.
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300难题 OG17
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Much of the hope for continued improvement of the economy lies in the projection of increasing consumer spending this year.
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300难题 OG17
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A site once used as an observatory by the Anasazi, ancient pueblo dwellers of New Mexico, has been recently discovered where patterns of light and shadow were employed to establish the precise limits of the positions of the Sun and Moon over a nineteen-year cycle.
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