由于时间长内容难信息量大milieubackground区别，托福听力讲座经常让很多学生头疼milieubackground区别，尤其是学生试图弄懂每句话时，总会因为高深的学术词汇而倍感压力。而实际上，在多年的托福听力真题中，我们发现大部分讲座的听力题目会出现在一些相对固定的地方。正如在学校听课时只要抓住老师讲解的重点，如果我们在听托福讲座时能把精力集中在出题点和重要信息上，不仅能准确理清结构，答题时不慌乱，更能够规避开听力中令人胆颤的高阶学术词汇，取得高分。
下面简单分析讲座结构中最重要的一种
谜团解释型讲座
谜团解释型讲座是托福听力讲座中一种常见的讲座结构。TPO1-34的篇章中有25篇，占milieubackground区别了近20%，涉及生物学（如TPO27-L3蜥脚类恐龙成功存活之谜）、自然科学（如TPO4-L3巨石移动之谜）、考古学（如TPO33-L1金字塔建造之谜）等多个学科。把握好谜团解释型讲座对托福听力文本的理解有着至关重要的作用。
谜团解释型讲座的结构通常为milieubackground区别：谜团——假设——实验验证——教授态度。
一．谜团
和大部分开门见山的讲座类似，谜团解释型讲座开头先介绍相关背景，提出的谜团即是全篇的主旨。含有how/why的问题，和puzzle/mystery/problem的句子往往就是全篇的主题。例如TPO4-L3的开头部分milieubackground区别：
We’ve been covering rocks and different types of rocks for the last several weeks. But next week we are going to do something a bit different. And to get started I thought I’d mention something that shows how uh…as a geologist, you need to know about more than just rocks and the structure of solid matter.
Moving rocks, you may have heard about them. It’s quite a mystery. Death valley is this desert plain, a dry lake bed in California surrounded by mountains and on the desert floor these huge rocks, some of them hundreds of pounds. And they move. They leave long trails behind them, tracks you might say as they move from one point to another. But nobody has been able to figure out how they are moving because no one has ever seen it happen. Now there are a lot oftheories…
开篇就介绍了背景：在死亡谷的巨石可以移动；然后提出问题how they are moving没有人知道。对应主旨题：
1. What does the professor mainly discuss?
A. His plans for research involving moving rocks.
B. A difference between two geological forces that cause rocks to move.
C. Theories about why desert rocks move.
D. Reasons why geologists should study moving rocks.
很容易得出C为正确选项。
二．假设
针对前文的谜团, 教授会给出几种假设猜想。这时要注意听theory/hypothesis/assumption等词，记好假设的具体内容。例如TPO15-L1的中间段：
Yes, and that's one of the hypotheses that was proposed, that the brain simply doesn't admit the unimportant information. The second hypothesis is that, yes, we do perceive everything, but the brain categorizes the information, and whatever is not relevant to what we are concentrating on gets treated as low priority.
序数词引出hypothesis，对应细节题：
3. What hypotheses about distraction and brain were Lavie’s experiments involving star fields designed to investigate? Click on two answers.
A. Whether the capacity of the brain to process irrelevant information varies from person to person.
B. Whether the brain perceives information that is irrelevant to the performance of a task.
C. Whether the brain deals with distractions by categorizing irrelevant information as low priority.
D. Whether the visual cortex is activated during the sensation of movement.
正确选项即为稍作同义替换的BC两项。
三．实验验证
针对每一个假设，会有相对的实验experiment进行分析验证。针对实验的细节有时会讲的很清楚，但重点是实验结果发现了什么，要注意find/discover/show/suggest等引出的实验结果。如TPO15-L1的实验：
So Lavie did another experiment, designed to look at this ability to concentrate better in the face of increased difficulty. This time she used brain scanning equipment to monitor activity in a certain part of the brain, the area called V5, which is part of the visual cortex, the part of our brains that processes visual stimuli. V5 is the area of the visual cortex that's responsible for the sensation of movement. Once again, Lavie gave people a computer-based task to do.
They have to distinguish between words in upper and lower-case letters or even harder, they had to count the number of syllables in different words. This time the distraction was a moving star field in the background, you know, where it looks like you are moving through space, passing stars. Normally area of V5 would be stimulated as those moving stars are perceived and sure enough, Lavie found that during the task area of V5 was active, so people were aware of the moving star field. That means people were not blocking out the distraction…Lavie also discovered that as she made the task more difficult , V5 became less active…
题目并没有涉及繁琐的实验细节，而只问了实验结果：
4. What did Lavie’s scans of subjects’ visual cortexes reveal?
A. Area V5 became less active when tasks became more difficult.
B. The presence of the star field did not affect activity in area V5.
C. Area V5 became more active as more information appeared on the screen.
D. Stimulating area V5 interfered with subjects’ ability to perceive motion.
根据discover的结果，选择A。
四．教授态度
实验完成后，讲座的叙述者教授，还会给出自己的观点opinion。考生根据常识，可能会觉得很多谜团都需要进一步研究further study，但是托福听力文本中的教授可能会给出确定的观点，比如The conclusion is strong./ This evidence is conclusive.等言论。这时就要我们根据原文选择符合的选项了。如TPO4-L3在实验完成后，教授说：
Some scientists theorized that perhaps when the ground is slippery the high winds can then move the rocks. There’s a problem with this theory. One team of scientists flooded an area of the desert with water, then try to establish how much wind force would be necessary to move the rocks. And get this: you need winds of at least five hundred miles an hour to move just the smallest rocks! And winds that strong have never been recorded. Ever! Not on this planet. So I think it’s safe to say that that issues has been settled.
对应态度题：
3. The professor mentions experiments on the wind speed necessary to move rocks. What is theprofessor’s attitude toward the experiments?
A. Their results were decisive.
B. They were not carried out carefully.
C. They were not continued long enough to reach a conclusion.
D. The government should not have allowed the experiments.
根据原文，应该选择A项。
从以上的分析中，我们也可以看出，谜团解释型讲座并不是单线条的。因为可能有多个假设，所以结构会扩展为：谜团——假设1——实验验证1——教授态度2——假设2——实验验证2——教授态度2……。但是万变不离其宗，只要考生注意，不要被实验细节的详细描述带偏了，把握住假设的内容、实验的结果和教授的态度，就能在答题时选对正确的选项。
作者简介：
赵璟 广外英语专业毕业，英语专业八级证书，从事出国考试培训行业2年，多次在托福考试中取得听力单科满分。
原文地址：https://www.onebest.cn/content-100-3267-1.html
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