正确答案是C,因为年轮上可以看出连续的六年干旱三年雨水三年干旱,而且所有的木头都是freshly cut,并且都来源于同一个山谷。如果考古学家知道历史上曾经有过“六年干旱三年雨水三年干旱”的历史时间(不过题目中没有明说),就能推出墓的时间。 另外ABDE好像和题目更加不相关,也可以用排除法排除掉。
A tree’s age can be determined by counting the annual growth rings in its trunk. Each ring represents one year, and the ring’s thickness reveals the relative amount of rainfall that year. Archaeologists successfully used annual rings to determine the relative ages of ancient tombs at Pazyryk. Each tomb was constructed from freshly cut logs, and the tombs builders were constrained by tradition to use only logs from trees growing in the sacred Pazyryk Valley. Which one of the following, if true, contributes most to an explanation of the archaeologists’ success in using annual rings to establish the relative ages of the tombs at the Pazyryk site? (A) The Pazyryk tombs were all robbed during ancient times, but breakage of the tombs seals allowed the seepage of water, which soon froze permanently, thereby preserving the tombs’ remaining artifacts. (B) The Pazyryk Valley, surrounded by extremely high mountains, has a distinctive yearly pattern of rainfall, and so trees growing in the Pazyryk Valley have annual rings that are quite distinct from trees growing in nearby valleys. (C) Each log in the Pazyryk tombs has among its rings a distinctive sequence of twelve annual rings representing six drought years followed by three rainy years and three more drought years. (D) The archaeologists determined that the youngest tree used in any of the tombs was 90 years old and that the oldest tree was 450 years old. (E) All of the Pazyryk tombs contained cultural artifacts that can be dated to roughly 2300 years ago. 答案稍后给出 -- by 会员 gedn01 (2010/2/18 13:14:07)
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