803.The period when the great painted caves at Lascaux and Altamira were occupied by Upper Paleolithic people has been established by carbon-14 dating, but what is much more difficult to determine are the reason for their decoration, the use to which primitive people put the caves, and the meaning of the magnificently depicted animals. (A) has been established by carbon-14 dating, but what is much more difficult to determine are (B) has been established by carbon-14 dating, but what is much more difficult to determine is (C) have been established by carbon-14 dating, but what is much more difficult to determine is (D) have been established by carbon-14 dating, but what is much more difficult to determine are (E) are established by carbon-14 dating, but that which is much more difficult to determine is
851.The work of mathematician Roger Penrose in the early 1970s, on the geometry of what are called aperiodic tiles, turned out to describe the architecture of a previously unknown class of crystals. (A) what are called aperiodic tiles, turned out to describe (B) what is called aperiodic tiles, describes (C) aperiodic tiles, describing (D) so-called aperiodic tiles, describe (E) aperiodic tiles, it turned out to describe
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发表于 2010-7-29 13:57:12
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