prep 2007 52题

晓春太阳

Dendrochronology, the study of tree-ring records to glean information about the past, is possible because each year a tree adds a new layer of wood between the existing wood and the bark.  In temperate and subpolar climates, cells added at the growing season's start are large and thin-walled, but later the new cells that develop are smaller and thick-walled; the growing season is followed by a period of dormancy.  When a tree trunk is viewed in cross section, a boundary line is normally visible between the small-celled wood added at the end of the growing season in the previous year and the large-celled spring wood of the following year's growing season.  The annual growth pattern appears as a series of larger and larger rings.  In wet years rings are broad; during drought years they are narrow, since the trees grow less.  Often, ring patterns of dead trees of different, but overlapping, ages can be correlated to provide an extended index of past climate conditions.
    However, trees that grew in areas with a steady supply of groundwater show little variation in ring width from year to year; these "complacent" rings tell nothing about changes in climate.  And trees in extremely dry regions may go a year or two without adding any rings, thereby introducing uncertainties into the count.  Certain species sometimes add more than one ring in a single year, when growth halts temporarily and then starts again.


52题：The passage is primarily concerned with
（A）evaluating the effect of climate on the growth of trees of different species
（B）questioning the validity of a method used to study tree-ring records
（C）explaining how climatic conditions can be deduced from tree-ring patterns
（D）outlining the relation between tree size and cell structure within the tree
（E）tracing the development of a scientific method of analyzing tree-ring patterns

答案选C，但B有什么地方不对啊？而且climate只是作为论述年轮的一个方面，并不是文章的主旨吧。。。
求高人解惑~~~

MarcDeu

文章应该讨论的是气候条件与树轮两者的关系啊，而不只是说研究树轮方式的有效性问题，直接依赖原文，不需要做进一步推理。

waihou32

文章的态度很明显是一个大正小负(以正态度为主）,因为第一句话就说了这个method是possible的,第二段用小篇幅去质疑它存在的一些缺陷,当然不能说实在questioning了