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今天我们来看一下最喜闻乐见的长难句—— 因果关系类：
1. Escape involves such actions as aestivation, a condition of prolonged dormancy, or torpor, during which animals reduce their metabolic rate and body temperature during the hot season or during very dry spells.
○ One way animals escape is by entering a state of extended dormancy, known as aestivation, during the hottest and driest times of year.
○ Animals can escape without using direct action, or aestivation, simply by reducing their metabolic rate and body temperature.
○ The actions that an animal uses to escape are known as aestivation, which sometimes involves a reduction in metabolic rate or body temperature.
○ When the weather is especially hot and dry, an animal may suffer from a condition known as aestivation, at which point the animal needs to escape.
原句中，escape involves aestivation, 后面解释aestivation=dormancy(torpor) = reduce metabolic rate & body temperature; 最后加一个时间点during...
看四个选项，1st选项中one way对应原句的involve, 后面说明escape包含dormancy或aestivation，省略了定语从句which修饰dormancy，但整体跟原句相符;2nd选项without…不对;3rd选项中 escape=actions=aestivation把escape的范围缩小了; 4th选项中 suffer from不对，不是遭受，而是主动选择;此外，也未解释escape。
碰到这种同位语或插入语很多的情况，一定要以读懂为主，不要纠结生词!
2. Learning appropriate social behaviors is especially important and species that live in groups, like young monkeys that needed to learn to control selfishness and aggression and to understand the give-and-take involved in social groups. ( 举例论证)
A. Only monkeys that have learned to control their selfish and aggressive behaviors can be involved in social groups.
B. Selfish and aggressive animals like monkeys live in groups in order to practice appropriate social behaviors.
C. Some monkeys are naturally too selfish and aggressive to understand the give-and-take of social groups, so they learn such important behaviors while young.
D. Monkeys and other social animals need to learn behaviors appropriate for their social groups.
原句中，前面是论点后面是论据，学习合适的社会行为对群居物种很重要，举猴子的例子。
选项中，D选项猴子和其他群居动物需要学习behaviors，符合原句。 A选项only就错了，用论据代替了论点;B选项in order to前后反了，是因为要群居，所以才practice behaviors; C选项直接说some monkeys，跟A选项一样，用例子代替论点，而且说错了
复习完毕，进入到因果关系类：
先闭上眼睛，默默回顾下有哪些词可以表达因果关系的?
马上想到的必须是because, 之后应该就是for, since, as, with, 等连接词，表示原因。此外还有表示结果的so, hence, thus等;有一个比较容易被忽略但会在阅读中出现频率非常高的是 ：v-ing, 也就是结果状语。
除此之外，还有美国人民非常爱用的so…that… ;
除了直接的因果关系词之外，还有表示导致/归因于的词大家要非常关注!包括 be responsible for…, cause, lead to, give rise to…, contribute to…,result in等;以及表示explain的account for…。
一下子丢出这么些词可能有些无从下手，我们来看下具体的题目：
1. Because the medium was so prolific, in the sense that it was possible to produce a multitude of images very cheaply, it was soon treated as the poor relation of fine art, rather than its destined successor.
O Photography did not replace other fine arts because people felt the image looked cheap in relation to the other arts.
O Photography was so cheap and readily available that it could be purchased by people who were too poor to purchase fine art.
O Photography not only spread quickly but also was a cheap art form and so became true successor of fine arts rather than its poor relation.
O Photography was not considered a true art because people could use it to create many images cheaply.
原句中，because表示因果，因为the medium非常prolific，后面in the sense that (在某种意义上因为)进一步补充prolific，prolific是因为produce cheaply;所以它被当成art的穷亲戚，而非继承者(rather...than...表对比)。
也就是说：因为medium便宜，所以多，所以不被当成fine art。
看选项，四个选项都有因果关系词，关键是把因和果匹配清楚;1st选项，说照片没有代替其他fine arts因为人们觉得图像看清来很便宜;结果对原因错，原因是照片真的便宜，不是看起来便宜。 2nd选项，so...that表示因果;照片太便宜以及太多，以至于买不起艺术品的人也能买;原因对，结果错，结果是不被当成艺术。 3rd选项，前面not only…but also表示并列，但spread quickly原句未提及;而且后面结果也说反了。 4th选项，照片不被当成true art因为它很便宜;虽然省略
最后，大家发现原句用的是medium，到选项却变成photography了，这个是个很好的paraphrase，用medium媒介这个词去替代photography。大家读文章的时候看到这种不太熟悉的词替换成相应的简单词去理解就好了。
2. Importing the grain, which would have been expensive and time consuming for the Dutch to have produced themselves, kept the price of grain low and thus stimulated individual demand for other foodstuffs and consumer goods.
○ Buying imported grain led to the Dutch demanding that other foodstuffs and consumer goods be imported.
○ Keeping the price of grain low was a primary goal of the Dutch at a time when they could not produce enough grain to provide for all their needs.
○ The demand for other foodstuffs and consumer goods forced the Dutch to import grain and other products at a time when maintaining low prices was especially important.
○ Because the Dutch were able to import inexpensive grain, they had money available to create a demand for other food products and consumer goods.
原句中，先不看插入的定语从句;进口谷物使价格变低，因此刺激(stimulated)个人对其他消费品的需求;定语从句里面说的是，谷物如果自己生产就会很贵。
简而言之，进口谷物使得对其他产品有需求。
选项中，1st选项，最后的other be imported信息不存在，原句只是说有需求，没有说更多进口需求;2nd选项， keeping price low是主要目标，因为他们不能产生足够多的谷物与原句不符(when表示原因);3rd选项，对其他消费品的需求forced荷兰人去进口谷物，谓语动词前后的关系说反了。4th选项，因为荷兰人进口便宜谷物，用一个inexpensive概括了插入语中的定语从句;后面说结果就是有钱买更多。