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GRE阅读考试模拟题及答案解析(1)

2016-03-10 18:31:15来源：网络

　　7

　　Finally, flux, which is sometimes added during smelting to remove waste material from the ore, could add quantities of elements to the final product.

　　最后，熔剂，加入到熔炼过程中用来从矿石中去除废料的一种物质，也会在成品中混入一定量的其他元素。

　　8

　　An elemental property that is unchanged through these chemical processes is the isotopic composition of each metallic element in the ore.

　　经过这些化学工艺，一个不变的性质是矿石中每种金属元素的同位素构成比例。

　　9

　　Isotopic composition, the percentages of the different isotopes of an element in a given sample of the element, is therefore particularly suitable as an indicator of the sources of the ore.

　　同位素构成，是某元素的一份样品中各种同位素所占的百分比，所以它特别适合作为鉴定矿石来源的指标。

　　10

　　Of course, for this purpose it is necessary to find an element whose isotopic composition is more or less constant throughout a given ore body, but varies from one copper ore body to another or, at least, from one geographic region to another.

　　当然，为了完成测定有必要找到这样一种元素，它在一块矿石中的同位素构成比例或多或少是稳定的，但在不同矿石，或不同地域出产的矿石中它的比例互相区别。

　　11

　　The ideal choice, when isotopic composition is used to investigate the source of copper ore, would seem to be copper itself.

　　当我们用同位素构成比例来调查铜矿石来源，理想的选择，似乎就是铜本身。

　　12

　　It has been shown that small but measurable variations occur naturally in the isotopic composition of copper.

　　我们已经知道铜的同位素构成在自然情况下会发生小但可测量的变化。

　　13

　　However, the variations are large enough only in rare ores; between samples of the common ore minerals of copper, isotopic variations greater than the measurement error have not been found.

　　然而，这种改变只有在稀有矿石中才足够大(可测量);普通铜矿物样本的同位素差异，一般都小于测量误差。

　　14

　　An alternative choice is lead, which occurs in most copper and bronze artifacts of the Bronze Age in amounts consistent with the lead being derived from the copper ores and possibly from the fluxes.

　　另一种选择是铅，在多数青铜时代的铜以及青铜制品中都含有铅，数量大体与铜矿石中的铅相当，也可能有部分来自熔剂。

　　15

　　The isotopic composition of lead often varies from one source of common copper ore to another, with variations exceeding the measurement error; and preliminary studies indicate virtually uniform isotopic composition of the lead from a single copper-ore source.

　　同类型来源的不同普通铜矿石中，铅的同位素比例通常不同，这种差异超过了测量误差的范围;且初步的研究显示，单一铜矿样本中的同位素比例实际上是一致的。

　　16

　　While some of the lead found in an artifact may have been introduced from flux or when other metals were added to the copper ore, lead so added in Bronze Age processing would usually have the same isotopic composition as the lead in the copper ore.

　　尽管有些制品中的铅可能来自于熔剂或熔炼铜矿过程中加入的其他金属，青铜时代工艺中这些被加入的铅，经常与铜矿中的铅有着相同的同位素比例。

　　17

　　Lead isotope studies may thus prove useful for interpreting the archaeological record of the Bronze Age. (473 words)

　　所以，铅的同位素研究可能帮助我们解释青铜时代的某些考古记录。

　　4. The author first mentions the addition of flux during smelting in the last sentencein the last paragraph in order to(在文章第14句)

　　(A) give a reason for the failure of elemental composition studies to determine ore sources

　　(B) illustrate differences between various Bronze Age civilizations

　　(C) show the need for using high smelting temperatures

　　(D) illustrate the uniformity of lead isotope composition

　　(E) explain the success of copper isotope composition analysis

　　选A

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