ACT科学推理样题解析.

　　ACT考试的Science(科学推理)部分旨在考查学生的理解、分析、审视、推理和解决问题的能力。这部分的分值的比重与其他三部分等同，都是36分。每次考试中，科学推理部分共7篇文章，每篇文章附5-7道选择题，要求学生在35分钟内完成40道题目。

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　　接下来本文就以Official Guide 当中的一篇文章及附带的6个问题为例，简要作一个分析，旨在让学生清楚地了解科学推理题目的基本解题思路。

　　Passage IV

　　Three studies were conducted to examine the relation shop between ants and acacia trees they inhabit.

　　解题的第一步首先是审题。第一步就是要读最前边的一段论述性文字，在这一步骤中，重点关注这篇文章的主体，也就是主要研究对象，这里当然也就是ants and acacia trees they inhabit。以下每个实验研究的介绍处理方法一样，扫读，重点关注其分别的次级研究对象就足够了。强调一点，次级研究对象一定是紧密围绕着主要研究对象的。以上就是我们对审题的要求。

　　Study 1

　　Table 1 shows the results of a comparison between a species of acacia tree that is inhabited by ants (ant trees) and a species that is not inhabited by ants (non-ant trees).

　　Table 1

　　Ant trees Non-ant trees

　　Leaves bitter-tasting chemicals absent

　　protein-bodies present bitter-tasting chemicals present

　　protein-bodies absent

　　Thorns specialized hollow thorns on stems no specialized thorns

　　Ants specific ant species living in thorns no ants living on trees

　　Exrafloral nectaries present absent

　　Trunk surrounded by bare ground surrounded by many other plants

　　﹡Nectar-producing (sugar-producing) structures located outside the flowers

　　Study 2

　　Table 2 shows the results of a comparison between acacia ant and a closely related ant species that does not inhabit acacia trees.

　　Table 2

　　Acacia ants Non-acacia ants

　　Aggressiveness very aggressive very aggressive

　　Active periods active day and night active during daylight only

　　Diet protein-bodies

　　nectar do not eat living plants

　　Nest site only in the thorns of ant trees in the ground

　　Study 3

　　Acacia trees were divided into three groups. Acacia ants were removed from the trees in group A, but were lt on the trees in Group B. Group C consisted of a species of non-ant acacia tree. All the trees were initially healthy and of similar size, the number of trees still alive in each group 300 days after the start of the study is shown in Table 3

　　Table 3

　　Group A Group B Group C

　　Day alive dead alive dead alive dead

　　1

　　300 38

　　10 0

　　28 39

　　28 0

　　11 40

　　30 0

　　10

　　Trees in Group A were killed by plant-eating insects and large mammals that ate the leaves on lower branches. There was no evidence that trees in Groups B and C were killed by grazing animals.

　　18. How is the designs of study 1 different from the design of study 2?

　　F. In study 1, acacia ants were removed from acacia trees, but not in Study 2.

　　G. in study 1, plant characteristics were examined, while in Study 2, ant characteristics were examined.

　　H. In study 1, acacia ants were examined, while in Study 2, non-acacia ants were examined.

　　J. In study 2, ant characteristics were examined, while in Study 2, plant characteristics were examined.

　　第一道题目往往比较简单。这里我们看到题目问的是Study1和2比较起来有什么不同?如果Study1和2的介绍和表格的内容来看，不同点有很多，那到底题目要求的不同点应该是那个呢?当然，问到实验设计的不同，一定是问的实验的目的和方法不同，这里也就是问其研究对象的不同，其他的差异，诸如实验结果，实验数据的差异不是题目的要求。那么这里，很明显答案是(G.)

　　19. On the basis of the experimental results, one can generalize that which of the following characteristics protects non-ant acacias from being eaten by insects or grazing animals?

　　A. Bitter-tasting chemicals

　　B. Protein bodies

　　C. Extrafloral nectaries

　　D. Specialized hollow thorns

　　19题，问是什么使non-ant acacias免于动物的啃噬，经过观察表格发现，B.C.D.选项，在non-ant acacias上都不曾出现，那么它们必然不能是造成这一现象的原因，正确答案是(A.) Bitter-tasting chemicals

　　bitter-tasting chemicals present

　　protein-bodies absent

　　no specialized thorns

　　absent

　　20. From the results of Study 2 the researchers would hypothesize that the ground surrounding the ant acacia trees was bare of vegetation because the:

　　F. acacia ants killed the plants growing near the ant acacia trees.

　　G. acacia ants killed the plants growing near the non-ant acacia trees.

　　H. non-acacia ants killed the plants growing near the non-ant acacia trees.

　　J. non-acacia ants killed the ant acacia trees.

　　这一题，问是推测可能是什么原因造成了ant acacia trees四周没有其他植物的现象，审题时关注的研究对象是ant acacia trees，那么大胆地判断，与之无关的选项必然都是错误的，都是答非所问的。直接可以排除G.H.J.,正确答案为(F.)，可能是acacia ant对ant acacia trees周围的植被起到了致命的影响，acacia ant同样是研究对象之间最大的差异，当然研究中首当其冲地会被怀疑是造成这一现象的原因。这里也体现了研究中的一个原则，即结果的差异一定是条件的差异造成的，只有存在差异的条件才可能导致结果的不同，简而言之，就是差异必然源于差异，但是差异不一定导致差异。

　　21. Can any conclusions about the relationship between plants and insects be drawn from the observations made on acacias and ants?

　　A. Yes; the behavior of different insect species toward plants seems to be the same.

　　B. Yes; some plants apparently provide shelter for the insects that protect them.

　　C. No; plants apparently have the same species of insects living on them.

　　D. No; insects are rarely associated with plants.

　　这道题目的研究对象是the relationship between plants and insects，那么回归文中提供的信息，一定是study 3提供给了我们根据，因为只有study 3的研究对象同时包含plants和insects。分析table 3: Group A, 本来与ant trees在失去了ant后，出现大量的死亡;Group B中ant trees在于ant共存的时候，死亡数量不多;得出结论，对于ant trees而言，ant trees能否生存和ant有很大的关系;而Group C中，non-ant trees没有ant仍然存活率较高;说明没有和ant形成共生关系的trees的存活情况则并不依赖ant.

　　那么观察选项，发现A.C.中存在same的字眼，基于观察到的各种差异性，这两个选项必然是不对的，而D.选型则是rarely associated，无关，这显然也不对。正确答案选择(B.)

　　根据20.题中的原则：差异源于差异，这里不难分析，一旦trees上出现了ant之后，它要生存就离不开ant了，同样，ant也需要植物给它提供生存的条件，如食物等;植物(trees)和昆虫(insects)之间形成了所谓的共生关系(symbiosis)，即彼此依存的关系，正是正确答案(B.)的内容。

　　22. Researchers removed all the insects from a tree that is different from the acacia. A comparison showed that few leaves were eaten both bore and after removal of the insects. Which of the following conclusions about the insects and the tree best explains these results?

　　A. The leaves were protected from grazing by some factor other than the insects.

　　B. Numerous vines grew over the tree and covered the leaves and stems.

　　C. The tree was unable to dend its leaves from attacks by grazing animals.

　　D. Aggressive insects attacked any potential grazers on the leaves of this tree.

　　这道题目中，经过对研究对象的把握和分析发现，研究对象是除了ant之外的其他昆虫和被吃掉的树叶，结果发现，其他昆虫的存在与否，不影响最后的结果，就是几乎没有树叶被吃掉。那么直接可以得出正确答案(F.) 与此同时，G.H.J的研究对象对于题目无关，故排除。

　　这道题同时也验证了20.题中给出的原则：结果的差异一定是条件的差异造成的，只有存在差异的条件才可能导致结果的不同;差异必然源于差异，但是差异不一定导致差异。

　　23. Which of the following conclusions about the function of protein bodies and extrafloral nectaries would be consistent with the results of the studies?

　　A. Protein bodies are used to deter grazing animals, while extrafloral nectaries are used as a food source by acacia ants.

　　B. Extrafloral nectaries are used to deter grazing animals, while protein bodies are used as a food source by acacia ants.

　　C. Both protein bodies and extrafloral nectaries are used to deter grazing animals.

　　D. Both protein bodies and extrafloral nectaries are used as food sources by acacia ants.

　　根据题目的研究对象protein和nectar，根据只能在study 1和study 2当中，因此选项A.B.C.都涉及了deter grazing animals，这是只有study 3才涉及的，明显的跨区选项，是study 1和2当中没有的信息，故排除。正确答案(A.) 根据表格2内容

　　Diet protein-bodies

　　nectar

　　很容易得出结论(A.)

　　以上就做完了一整篇文章的题目，总结起来，对ACT科学推理部分的题目，应对策略主要是：

　　一.审题：确定研究对象(以便排除与研究对象无关的干扰选项)。

　　二.分析研究对象之间的关系，掌握科学的研究分析原则

　　次级研究对象一定是紧密围绕着主要研究对象的

　　结果的差异一定是条件的差异造成的，只有存在差异的条件才可能导致结果的不同;差异必然源于差异，但是差异不一定导致差异。

　　……

　　三.观察选项：找到突破口。

　　而具体的解题步骤，归纳以来如下：

　　a) 读前面综述

　　b) 扫读具体的实验、研究和理论

　　c) 读题目，根据次级研究对象回文中定位

　　d) 分析选项，选择答案

　　而平时的准备过程中，考生们如果能好好吸收课堂上老师讲解的方法和原则，课后要做的工作实际上不是非常多，不需要大家广泛涉猎，学习和背诵大量的背景。从上面一篇文章可以看出，通篇，没有对任何一个专业术语做出翻译和解释，但是题目同样可以迎刃而解，至于acacia trees, acacias ants是什么的，能知道的人可以说寥寥无几，但是这些根本无关紧要。

　　从语言的角度上来讲，ACT Scientific Reasoning Test相对于SAT考试对英语，词汇的要求来的要低，大家只要认真地多加练习，在有托福的基础的前提下，这部分语言应该不会有太大的问题。

　　以上就是关于ACT考试科学推理部分样题解析。提醒考生们不能掉以轻心，因为这部分的时间紧张，要求大家对题目的问法有较强的敏感度，并且对解题过程有相对较高的熟练度，否则就会做不完题目，让分数白白跑掉。