结构题要求你分析和评价文章的组织和逻辑。结构题可能会问到一篇文章是如何构造的。例如，哪里在定义;哪里在进行比较和对照;哪里在表达新观点;哪里在反驳一个观点。结构题也可能会问到作者是如何说服读者接受自己的主张的，或者作者使用某个特别的支撑细节的原因。结构题还可能要求你识别作者所做的假设，或者要求你评估作者的论证的力度和缺陷，或者要求你找出合适的驳论。结构题不仅测试你理解文章的能力，还测试你准确地评价文章的能力。然而，对你来说非常重要的是你必须明白，这类问题既不需要你依赖于任何规整的逻辑，也不需要你熟悉逻辑和论证方面的专门术语。你回答这些问题，只需要用到文中所提到的信息并进行仔细的推理。Types of logicalstructures often used in GMAT
1. A comparison orcontrast between two events, ideas, phenomena or people.
2. One theory or idea illustrated with several detailed examples or illustrations(often one example or illustration per paragraph)
3. One theory or idea supported by several arguments (often one argumentper paragraph)
4. Several theories or approaches to a single question or topic (often onetheory or approach per paragraph)
5. Pro and Con arguments presented on both sides of a single issue
6. A cause-effect sequence showing how one event led to another (presentedeither in chronological order or via flashback with later events named beforethe earlier ones)
例：Passage 20 (20/63)
Speciesinterdependence in nature confers many benefits on the species involved, but itcan also become a point of weakness
when one species involved in the relationship is affected by a catastrophe. Thus,flowering plant species dependent on insect pollination, as opposed toself-pollination or wind pollination, could be endangered when the populationof insect-pollinators is depleted by the use of pesticides.
In theforests of New Brunswick(名字要记住，简记为NB-举例，预期下面要出细节题), forexample, various pesticides have been sprayed in the past 25 years in effortsto control the spruce budworm, an economically significant pest. Scientistshave now investigated the effects of the spraying of Matacil,one of the anti-budworm agents that is leasttoxic(比较举例分析的这种spraying和其它的spraying的关系，预期有比较关系，做推断的题)toinsect-pollinators. They studied Matacil’s effects on insect mortality in awide variety of wild insect species and on plant fecundity,expressedas the percentage of the total flowers on an individual plant that actuallydeveloped fruit and bore seeds.(我读出要授粉后才会产生果实，所以用果实的percentage来读出fecundity这个词和pollination产生关系，那么逻辑图:spraying
影响insect-pollinator,主要是减少，->减少授粉->果实减少)They found that the most pronounced mortality after the spraying of Matacil occurred among thesmaller bees and one family of flies, insects that were all importantpollinators of numerous species of plants growing beneath the tree canopy offorests. The fecundity of plants in one common indigenous species, thered-osier dogwood, was significantly reduced in the sprayed areas as comparedto that of plants in control plots where Matacil was not sprayed. This speciesis highly dependent on the insect-pollinators most vulnerable to Matacil. Thecreeping dogwood, a species similar to the red-osier dogwood, but which ispollinated by large bees, such as bumblebees, showed no significant decline infecundity. Since large bees are not affected by the spraying of Matacil, theseresults add weight to the argument that spraying where the pollinators aresensitive to the pesticide used decreases plant fecundity.
The question of whether the decrease in plant fecunditycaused by the spraying of pesticides actually causes a decline in the overallpopulation of flowering plant species still remains unanswered.
(第三段的中心意思)Plantspecies dependent solely on seeds for survival or dispersal are obviously morevulnerable to any decrease in plant fecundity that occurs, whatever its cause.If, on the other hand, vegetative growth and dispersal (by means of shoots orrunners) are available as alternative reproductive strategies for a species,then decreases in plant fecundity may be of little consequence. The fecundityeffects described here are likely to have the most profound impact on plant specieswith allfour of the following characteristics(列举一般下面会出题):
a shortlife span, a narrow geographic range, an incapacity for vegetative propagation,and a dependence on a small number of insect-pollinator species.
Perhapswe should give special attention to the conservation of such plant speciessince they lack key factors in their defenses against the environmentaldisruption caused by pesticide use.
1. Which of the following best summarizesthe main point of the passage?
(A) Species interdependence is a point of weakness for someplants, but is generally beneficial to insects involved in pollination.
(B) Efforts to control the spruce budworm have had deleteriouseffects on the red-osier dogwood.
(C) The used of pesticides may be endangeringcertain plant species dependent on insects for pollination.************
(D) The spraying of pesticides can reduce the fecundity of aplant species, but probably does not affect its overall population stability.
(E) Plant species lacking key factors in their defenses againsthuman environmental disruption will probably become extinct.
2. According to the author, a floweringplant species whose fecundity has declined due to pesticide spraying may notexperience an overall population decline if the plant species can do which ofthe following?
(A) Reproduce itself by means of shoots and runners.
(B) Survive to the end of the growing season.
(C) Survive in harsh climates.
(D) Respond to the fecundity decline by producing more flowers.
(E) Attract large insects as pollinators.