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2011年下半年大学英语六级考试阅读考试训练七

2011-11-14 阅读 :

 Leonardo da Vinci was the first man to suggest that growing trees add a new ring in their trunks each year. The   11   in these rings relates to the physical conditions which the tree experiences. Thus, trees grown in a   12   area and time each develop a pattern or configuration of their rings.

  This  13  was of little significance until Andrew E. Douglas began to study tree rings in Arizona in 1900. Using a technique called cross dating, he was able to employ tree rings to the study of archaeological sites and date the ruins with  14   . Some were as old as 6700 B. C. ! This study of tree rings is called dendrochronology.

  In time the cross dating was   15  by a carbon 14 process. This approach measured the amount of carbon 14 radiating from a piece of wood and   16   to determine the age of that wood. Further use of the carbon 14 technique has shown that the radiation process is more complex and less  17  than had been at first thought.

  The most  18  aspect of tree ring research is now called

  dendroclimatology. This   19  of the reconstruction of climates and climatic cycles and events from the evidence found in the tree rings. From this it is hoped that a   20  of drought cycles can be determined in the American Southwest. Such information will be of great help in determining the life and ecology of that region of the United States.

   

  A. thus B. model

   C. variation D. concept

 E. accuracy F. exciting

   G. consists H. given

  I. proposition J. composes

   K. further L. pattern

 M. supplemented N. reliable

   O. excellent

本文标题:2011年下半年大学英语六级考试阅读考试训练七
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