托福听力怎么运用转折关系准确的选择答案

托福界流行一句话叫“得听力者，得托福”,这句话强调的是听力在托福考试中的重要地位。在托福考试中，除了阅读，其他三项全都要考察听力能力，因此Listening这个部分的难度就更不用说了，四项中较难。
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托福听力lecture当中往往会涉及到一些理论、方法、原因等的分析和探讨，而在每一个观点内部又充满了各类逻辑关系和语义连接。今天给大家分享的是如何利用转折关系、准确的选定答案。
先来看一道题目：
（TPO 33 L1）
According to the professor, what is the main argument against the theory that the stone blocks of the Great Pyramid were lifted into place with cranes?
A. Wood Cranes would have been too weak to lift the blocks.
B. There is no evidence of ancient Egyptians ever using cranes.
C. The use of cranes would have resulted in imprecise dimensions.
D. There would not have been enough room for a platform for the cranes.
解题思路：
每当题目询问的是一个理论的缺陷的时候，我们便去回忆这段录音中，该理论出现时转折关系后的内容作为我们的答案，原文：理论：His theory was that cranes were used, much like we use cranes today to construct tall buildings. And Herodotus may have seen Egyptians using cranes made of wood.
转折：But the problem with this theory has to do with simple mechanics. A crane needs a wide and sturdy base to stand on or it will fall over. Well, as you get toward the top of the Pyramid, there's really no place for a crane to stand. The stone blocks are too narrow to provide a base. Well, so much for that theory.根据转折后划线部分内容判定，理论不成立的原因在于金字塔顶部并没有足够大的空间来搭建cranes。于是正确答案为D。
那么按照这样的解题思路，我们再来反向梳理一下，当题目问及为何要提到转折后的信息时，答案有应该是什么呢？自然是为了反驳转折前的理论。
再来看题：
Why does the professor talk about the accuracy of the proportions of the Great Pyramid?
A. To provide background on the principles of microgravimetry
B. To discount the possibility that a ramp once spiralled around outside of the pyramid
C. To explain the effectiveness of computer models of the pyramid
D. To emphasize the difficulty of building a ramp with the correct slope
原文：理论：So why not wrap the ramp around the Pyramid? Building the ramp around it as you go? Sounds like a pretty good idea. 转折：Except it's got a serious problem. See, one of the most remarkable things about the Great Pyramid is how accurate the proportions are.
The dimensions are almost perfect. To g