主旨题做题技巧
（一）、例子不能作为文章主旨
根据“串线法”可知，文章的主旨不是在文章中出现一次或两次的信息，而是在文章中重复出现的信息。但有时候，有些例子会反复在文章中出现，以至于同学们会误解这个反复出现的例子就是文章主旨。事实上，在五大微读一节中我们讲过，例子都是为了论点服务的，故即便某个例子在文章中反复出现，但是因为它只是论证论点，故不能作为文章主旨。
例：09年四川卷E篇
P1：All too often ， a choice that seems sustainable（可持续的）turns out on closer examination to be problematic. Probably the best example is the rush to produce ethanol（乙醇）for fuel from corn . Corn is a renewable resource -you can harvest it and grow more， almost limitlessly . So replacing gas with corn ethanol seems like a great idea .
P2：One might get a bit more energy out of the ethanol than that used to make it， which could still make ethanol more sustainable than gas generally， but that’s not the end of the problem. Using corn to make ethanol means less corn is left to feed animals and people， which drives up the cost of food. That result leads to turning the fallow land - including， in some cases， rain forest in places such as Brazil - into farmland， which in turn gives off lots of carbon dioxide（CO2）into the air. Finally， over many years， the energy benefit from burning ethanol would make up for the forest loss. But by then， climate change would have progressed so far that it might not help.
P3：You cannot really declare any practice “sustainable” until you have done a complete lift-cycle analysis of its environmental（环境的）costs. Even then， technology and public policy keep developing， and that development can lead to unforeseen and undesired results. The admirable goal of living sustainable requires plenty of thought on an ongoing basis.
60. What does the author mainly discuss in the text？
A. Technology. B. Sustainability.
C. Ethanol energy. D. Environmental protection.
解析：由本题题干可知，此题属于主旨题。文章中“ethanol”重复出现。但是“ethanol”不能作为文章主题。因为从第一段第二句 “Probably the best example is the rush to produce ethanol（乙醇）for fuel from corn .”可知，“ethanol”是文章的例子，不可作为文章主旨。故C选项错误。
本文来源：网易教育频道综合
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王晓易_NE0011
