关注微信领¥50

百门课程¥0元


50万+已关注

GRE阅读模拟在线练习附答案一百三十八

2018-09-01 14:07:00来源:网络

  GRE阅读真题是大家复习备考中必备的资料,利用真题进行模拟考试的练习,可以帮助我们发现备考中的不足,重点来复习自己的短板,从而提升GRE阅读的速度,提高我们的分数。

点击查看》》》【GRE阅读真题在线练习附答案汇总】

  The determination of the sources of copper ore used in the manufacture of copper and bronze artifacts of Bronze Age civilizations would add greatly to our knowledge of cultural contacts and trade in that era. Researchers have analyzed artifacts and ores for their concentrations of elements, but for a variety of reasons, these studies have generally failed to provide evidence of the sources of the copper used in the objects. Elemental composition can vary within the same copper-ore lode, usually because of varying admixtures of other elements, especially iron, lead, zinc, and arsenic. And high concentrations of cobalt or zinc, noticed in some artifacts, appear in a variety of copper-ore sources. Moreover, the processing of ores introduced poorly controlled changes in the concentrations of minor and trace elements in the resulting metal. Some elements evaporate during smelting and roasting; different temperatures and processes produce different degrees of loss. Finally, flux, which is sometimes added during smelting to remove waste material from the ore, could add quantities of elements to the final product.

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

  The ideal choice, when isotopic composition is used to investigate the source of copper ore, would seem to be copper itself. It has been shown that small but measurable variations occur naturally in the isotopic composition of copper. 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. 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. 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 is topic composition of the lead from a single copper-ore source. 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. Lead isotope studies may thus prove useful for interpreting the archaeological record of the Bronze Age.

  The primary purpose of the passage is to

  A.discuss the techniques of analyzing lead isotope composition

  B.propose a way to determine the origin of the copper in certain artifacts

  C.resolve a dispute concerning the analysis of copper ore

  D.describe the deficiencies of a currently used method of chemical analysis of certain metals

  E.offer an interpretation of the archaeological record of the Bronze Age

  The author first mentions the addition of flux during smelting (lines 27-31) in order to

  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

  正确答案:B A

  以上就是关于“GRE阅读模拟在线练习附答案一百三十八”的内容,更多精彩内容,请关注GRE频道!


本文关键字: GRE阅读练习 GRE阅读 GRE

更多>>
  • GRE阅读考试如何提高阅读速度

      为了帮助大家高效备考GRE,新东方在线GRE频道为大家带来GRE阅读考试如何提高阅读速度,希望对大家GRE备考有所帮助。更多精彩尽请关注新

    来源 : 网络 2018-10-17 16:16:50 关键字 : GRE阅读速度 GRE阅读 GRE

  • GRE逻辑阅读备考方法

      为了帮助大家高效备考GRE,新东方在线GRE频道为大家带来GRE逻辑阅读备考方法,希望对大家GRE备考有所帮助。更多精彩尽请关注新东方在线

    来源 : 网络 2018-10-16 15:46:55 关键字 : GRE逻辑 GRE阅读

  • GRE阅读对比题型全面解析

      为了帮助大家高效备考GRE,新东方在线GRE频道为大家带来GRE阅读对比题型全面解析,希望对大家GRE备考有所帮助。更多精彩尽请关注新东方

    来源 : 网络 2018-10-15 17:27:00 关键字 : GRE阅读题型 GRE阅读 GRE

  • GRE阅读复习常用的猜词技巧

      为了帮助大家高效备考GRE,新东方在线GRE频道为大家带来GRE阅读复习常用的猜词技巧,希望对大家GRE备考有所帮助。更多精彩尽请关注新东

    来源 : 网络 2018-10-12 17:56:00 关键字 : GRE阅读技巧 GRE阅读

  • GRE阅读长难句的练习方法

      为了帮助大家高效备考GRE,新东方在线GRE频道为大家带来GRE阅读长难句的练习方法,希望对大家GRE备考有所帮助。更多精彩尽请关注新东方

    来源 : 网络 2018-10-11 17:56:00 关键字 : GRE阅读长难句 GRE阅读

  • GRE阅读词汇积累

      为了帮助大家高效备考GRE,新东方在线GRE频道为大家带来GRE阅读词汇积累,希望对大家GRE备考有所帮助。更多精彩尽请关注新东方在线GRE

    来源 : 网络 2018-10-10 17:56:00 关键字 : GRE阅读词汇 GRE

  • GRE阅读短篇文章练习

      为了帮助大家高效备考GRE,新东方在线GRE频道为大家带来GRE阅读短篇文章练习,希望对大家GRE备考有所帮助。更多精彩尽请关注新东方在线

    来源 : 网络 2018-10-09 17:56:00 关键字 : GRE阅读文章 GRE阅读

  • GRE阅读文章遇到生词怎么办

      为了帮助大家高效备考GRE,新东方在线GRE频道为大家带来GRE阅读文章遇到生词怎么办,希望对大家GRE备考有所帮助。更多精彩尽请关注新东

    来源 : 网络 2018-10-08 17:56:00 关键字 : GRE阅读生词 GRE阅读

  • GRE阅读考试技巧整理

      为了帮助大家高效备考GRE,新东方在线GRE频道为大家带来GRE阅读考试技巧整理,希望对大家GRE备考有所帮助。更多精彩尽请关注新东方在线

    来源 : 网络 2018-10-07 17:56:00 关键字 : GRE阅读技巧 GRE阅读 GRE

  • GRE阅读解题步骤助力高分

      为了帮助大家高效备考GRE,新东方在线GRE频道为大家带来GRE阅读解题步骤助力高分,希望对大家GRE备考有所帮助。更多精彩尽请关注新东方

    来源 : 网络 2018-10-06 17:56:00 关键字 : GRE阅读步骤 GRE阅读

更多内容
更多>>

GRE词汇营第二季

GRE高频词汇GRE填空必背

5天搞定800组GRE近/反义词

价格 : ¥19.9

30人 已报名

查看详情
更多>>
更多公开课>>
更多>>
更多课程>>