4as，such as 等举例
题目大部分是出现在前面的，少数后面情况：小部分由分号，so，hence，thus，代词it，they，their（说明前文话没说完）等理论指示性功能词引出。这样的话，我们是否更应该对主旨的样子有个基本感觉呢？这样对我们识别主旨，理论方面*出了主动性要求：大家一定注意附近相关这些词：because，so，however，second，at the same time（分层词）等功能词及其近义词；对每篇文章来讲，都有相对应的主旨句子的样子：分析现象的，主旨就是factor，perpaps，explanation，等引起的理论句子；分析事物的，就是事物各个方面概述性质的次描述；分析考古的，就是理论+"什么什么发现"或化石的evidence等。
Paragraph 5: Dependence on long-distance trade also meant that the great empires of the Middle East were built both literally and figuratively on shifting sand. The central state, though often very rich and very populous, was intrinsically fragile, since the development of new international trade routes could undermine the monetary base and erode state power, as occurred when European seafarers circumvented Middle Eastern merchants after Vasco da Gama''s voyage around Africa in the late fifteenth century opened up a southern route. The ecology of the region also permitted armed predators to prowl the surrounding barrens, which were almost impossible for a state to control. Peripheral peoples therefore had a great advantage in their dealings with the center, making government authority insecure and anxious.
12.In paragraph 5, why does the author mention the new trade route opened up by Vasco da Gama''s fifteenth century voyage around Africa?
○To provide evidence that European seafarers took every opportunity to bypass Middle Eastern merchants
○To present an instance in which Middle Eastern states lost money and power because of their reliance on long-distance trade
○To argue this new route became necessary when European seafarers wanted to avoid Middle Eastern states whose central power had begun to erode
○To explain how da Gama helped European traders avoid the dangerous predators prowling the areas surrounding Middle Eastern cities
考察点通过大写人名就很容易确定位置，在前面我们发现了一个词since，我们优先看since the development of new international trade routes could undermine the monetary base and erode state power
主干含义为：新国际贸易发展 undermine 钱和power。根据同义找答案。Undermine,分析词根，下的，不好的，mine，开矿，有种颠覆之感。对应答案，找一致表达含义的答案，选B. （补充词汇：undermine实际就是破坏）
Paragraph 3: Most lightning takes place within a cloud when the charge separation within the cloud collapses. However, as the storm cloud develops, the ground beneath the cloud becomes positively charged and lightning can take place in the form of an electrical discharge between the negative charge of the cloud and the positively charged ground. Lightning that strikes the ground is the most likely to be destructive, so even though it represents only 20 percent of all lightning, it has received a lot of scientific attention.
7.The author remarks that "Lightning that strikes the ground is the most likely to be destructive" in order to explain why
○ this form of lightning has been investigated so much
○ this form of lightning is not as common as lightning within a cloud
○ scientific understanding of this form of lightning is important
○ the buildup of positive charge on the ground beneath a storm cloud can have serious consequences
这个题目，按照一般思路的话，原文是"…是*有破坏性的"，后面明显出现了so，作为修辞目的题，我们就要关注了。在even though it represents only 20 percent of all lightning, it has received a lot of scientific attention.在eventhough部分，我们是不看的（让步状不说主要），那我们就看到了动宾结构：received scientific attention.我们预测，答案中肯定有"受到科学关注"这个含义的原词或同义改写，轻松选A.
Another prominent feature of Mars''s surface is cratering. The Mariner spacecraft found that the surface of Mars, as well as that of its two moons, is pitted with impact craters formed by meteoroids falling in from space. As on our Moon, the smaller craters are often filled with surface matter-mostly dust-confirming that Mars is a dry desert world. However, Martian craters get filled in considerably faster than their lunar counterparts. On the Moon, ancient craters less than 100 meters across (corresponding to depths of about 20 meters) have been obliterated, primarily by meteoritic erosion. On Mars, there are relatively few craters less than 5 kilometers in diameter. The Martian atmosphere is an efficient erosive agent, with Martian winds transporting dust from place to place and erasing surface features much faster than meteoritic impacts alone can obliterate them.
According to paragraph 4, what is demonstrated by the fact that craters fill in much faster on Mars than on the Moon?
A. Erosion from meteoritic impacts takes place more quickly on Mars than on the Moon.
B. There is more dust on Mars than on the Moon.
C. The surface of Mars is a dry desert.
D. Wind is a powerful eroding force on Mars.
拿到题目，我们需要先去分析题干：what is demonstrated by the fact，就是说通过一个事实说明了什么问题。既然是通过事实说明的，必然就是例子craters fill in much faster on Mars说明了什么理论，还是找理论部分。我们的问题部分所在位置由however引出，所以前文肯定是相反内容，不能作为一致倾向；只能向后找：后面说月亮直径小于100米；火星没有小于5公里的，就是说它大。不管你是否读懂了文章，先找*近的是否有这个主干；答案中没有；那我们继续向后看：The Martian atmosphere is an efficient erosive agent, with Martian winds transporting dust from place to place and erasing surface features much faster than meteoritic impacts alone can obliterate them.说大气腐蚀性，风力怎么样；刚好能对前文火星什么的被填充的快的解释；所以我们找大气腐蚀性，风吹dust一类描述就对了。这样就得选D了。