雅思阅读机经分析

                                   南京环球教育教研中心-陈居强

考试日期：

2014年7月26日

Reading Passage 1 (新）

Title:

Plastic

Question types:

填空 6

判断 （TFN）7

部分答案

填空答案

1. photographic film

2. bakelite 一种塑料的名字

3. Britain

4. fireproof

5. glass

6. foam

文章大意

大意就是不同的塑料种类，不同的性质，和不同的用途。

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剑桥真题5test2passage1

bakelite-the birth of modern plastic

Most plastics contain organic polymers. The vast majority of these polymers are based on chains of carbon atoms alone or with oxygen, sulfur, or nitrogen as well. The backbone is that part of the chain on the main "path" linking a large number of repeat units together. To customize the properties of a plastic, different molecular groups "hang" from the backbone (usually they are "hung" as part of the monomers before the monomers are linked together to form the polymer chain). The structure of these "side chains" influence the properties of the polymer. This fine tuning of the repeating unit's molecular structure influences the properties of the polymer.

Most plastics contain other organic or inorganic compounds blended in. The amount of additives ranges from zero percentage (for example in polymers used to wrap foods) to more than 50% for certain electronic applications. The average content of additives is 20% by weight of the polymer[citation needed].

Many of the controversies associated with plastics are associated with the additives.[3] Organotin compounds are particularly toxic.[4]

Fillers

Fillers improve performance and/or reduce production costs. Stabilizing additives include fire retardants to lower the flammability of the material. Many plastics contain fillers, relatively inert and inexpensive materials that make the product cheaper by weight.

Typically fillers are mineral in origin, e.g., chalk. Some fillers are more chemically active and are called reinforcing agents. Other fillers include zinc oxide, wood flour, ivory dust, cellulose and starch.[5]

Plasticizers

Since many organic polymers are too rigid for particular applications, they are blended with plasticizers (the largest group of additives[4]), oily compounds that confer improved rheology.

Colorants

Colorants are common additives, although their weight contribution is small.

Plastics are usually classified by their chemical structure of the polymer's backbone and side chains. Some important groups in these classifications are the acrylics, polyesters, silicones, polyurethanes, and halogenated plastics. Plastics can also be classified by the chemical process used in their synthesis, such as condensation, polyaddition, and cross-linking.[6]

Thermoplastics and thermosetting polymers

There are two types of plastics: thermoplastics and thermosetting polymers. Thermoplastics are the plastics that do not undergo chemical change in their composition when heated and can be molded again and again. Examples include polyethylene, polypropylene, polystyrene and polyvinyl chloride.[7] Common thermoplastics range from 20,000 to 500,000 amu, while thermosets are assumed to have infinite molecular weight. These chains are made up of many repeating molecular units, known as repeat units, derived from monomers; each polymer chain will have several thousand repeating units.

Thermosets can melt and take shape once; after they have solidified, they stay solid. In the thermosetting process, a chemical reaction occurs that is irreversible. The vulcanization of rubber is a thermosetting process. Before heating with sulfur, the polyisoprene is a tacky, slightly runny material, but after vulcanization the product is rigid and non-tacky.

Other classifications

Other classifications are based on qualities that are relevant for manufacturing or product design. Examples of such classes are the thermoplastic and thermoset, elastomer, structural, biodegradable, and electrically conductive. Plastics can also be classified by various physical properties, such as density, tensile strength, glass transition temperature, and resistance to various chemical products.

Biodegradability

Main article: Biodegradable plastic

Biodegradable plastics break down (degrade) upon exposure to sunlight (e.g., ultra-violet radiation), water or dampness, bacteria, enzymes, wind abrasion, and in some instances, rodent, pest, or insect attack are also included as forms of biodegradation or environmental degradation. Some modes of degradation require that the plastic be exposed at the surface, whereas other modes will only be effective if certain conditions exist in landfill or composting systems. Starch powder has been mixed with plastic as a filler to allow it to degrade more easily, but it still does not lead to complete breakdown of the plastic. Some researchers have actually genetically engineered bacteria that synthesize a completely biodegradable plastic, but this material, such as Biopol, is expensive at present.[8] Companies have made biodegradable additives to enhance the biodegradation of plastics.

Natural vs synthetic

Main article: Bioplastic

Most plastics are produced from petrochemicals. Motivated by the finiteness of petrochemical reserves and threat of global warming, bioplastics are being developed. Bioplastics are made substantially from renewable plant materials such as cellulose and starch.[9]

In comparison to the global consumption of all flexible packaging, estimated at 12.3 million tonnes/year, estimates put global production capacity at 327,000 tonnes/year for related bio-derived materials.[10][11]

Crystalline vs amorphous

Some plastics are partially crystalline and partially amorphous in molecular structure, giving them both a melting point (the temperature at which the attractive intermolecular forces are overcome) and one or more glass transitions (temperatures above which the extent of localized molecular flexibility is substantially increased). The so-called semi-crystalline plastics include polyethylene, polypropylene, poly (vinyl chloride), polyamides (nylons), polyesters and some polyurethanes. Many plastics are completely amorphous, such as polystyrene and its copolymers, poly (methyl methacrylate), and all thermosets.

Reading Passage 2旧

Title:

Intelligence and giftness心理学

Question types:

段落大意配对 3

单选 4

判断 YNN 6

部分答案

单选答案

文章作者的 purpose

——IQ 测试的 limitation

发明 IQ 测试的目的

——测试出同年龄段表现不太好需要特殊帮助的

测试 focus on 哪个方面

A reading skill

B mathematic skill

C 根据年纪

D people from different social background have different results

17 Recent study 是怎么考量 IQ 的——把 IQ 作为一个 separate element 在不同环境下考虑

判断题

只能在巴黎学校使用 NG

IQ test 也被 army 用在 different purpose 使用 Y

IQ 其实是不能按照一个固定的因素去测量的 Y

测试学生的时候应该从学习能力和技能来测试，不仅仅是 intelligence Y

文章大意

IQ测试的不同方面。

补充阅读

An intelligence quotient, or IQ, is a score derived from one of several standardized tests designed to assess human intelligence. The abbreviation "IQ" was coined by the psychologist William Stern for the German term Intelligenz-quotient, his term for a scoring method for intelligence tests he advocated in a 1912 book.[1] When current IQ tests are developed, the median raw score of the norming sample is defined as IQ 100 and scores each standard deviation (SD) up or down are defined as 15 IQ points greater or less, although this was not always so historically.[2] By this definition, approximately 95 percent of the population scores an IQ between 70 and 130, which is within two standard deviations of the mean.

IQ scores have been shown to be associated with such factors as morbidity and mortality,[3][4] parental social status,[5] and, to a substantial degree, biological parental IQ. While the heritability of IQ has been investigated for nearly a century, there is still debate about the significance of heritability estimates[6][7] and the mechanisms of inheritance.[8]

IQ scores are used as predictors of educational achievement, special needs, job performance and income. They are also used to study IQ distributions in populations and the correlations between IQ and other variables. Raw scores on IQ tests for many populations have been rising at an average rate that scales to three IQ points per decade since the early 20th century, a phenomenon called the Flynn effect. Investigation of different patterns of increases in subtest scores can also inform current research on human intelligence.

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Reading Passage 3 (新题)

Title:

Traveling plants生物

Question types:

配对 7（植物名称和特点细节配对）

填空 6

选择 1

部分答案

填空题答案

ants

nests

fruit

stone

cones

memory

选择题

这篇文章的意：C. 植物的生长是取决于环境的

文章大意

文章大意 植物不是固定的， 它的种子会到不同的地方生长；举例了很多种植物，以不同的方式散播种子，成长的方式也是不一样的

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There has been debate over how plant populations move under rapid climate change situations.[2][3] This debate stems from an issue called "Reid's paradox of rapid plant migration".[2] After the last glacial period, tree species spread to recover the newly exposed land. Through studies, it was calculated that this expansion occurred faster than perceived possible.[4] The two explanations for this rapid movement of forest populations across the landscape that came to the forefront were the retention of low-density founder populations and long distance migration.[2][3][5]

Retention of low-density founder populations[edit]

In this theory, small forest populations were retained within the affected region of the last glacial period.[3] The repopulation of this region, after the recession the glaciers, manifested as a relatively slow expansion outward of these retained populations. The expansion was mostly due to diffusion in a normal distribution from the reproductive core. The expansion of these populations was then dictated by the dispersal ability of the population. Through this process, waves of short distance expansion were seen over time as seeds dispersed, grew, matured, and set seed themselves. High rates of spread, similar to those obtained under the long distance migration assumption, have been obtained with diffusion models incorporating low-density founder populations.[5]

Range limits of many plant species are expected to shift dramatically if climatic warming, driven by the release of greenhouse gases, occurs in the next century. The ability of species to migrate in response to the range shifts has been questioned, especially in the context of extensive habitat fragmentation which occurs in modern-day landscapes.

Simulation models are presented which incorporate two factors, land use pattern and means of dispersal, to assess potential responses of forest species to climatic warming. Study areas displayed a range of human influence on the landscape, from heavily forested areas to areas dominated by urbanization and agriculture. The effect of establishing corridors (greenways) through fragmented landscapes is also assessed.

Results indicate that many species may be unable to track shifts in climatically-controlled range limits, resulting in widespread disequilibrium between vegetation and climate. A variety of mitigating options likely will be necessary to offset the negative consequences of climatic warming on biological diversity. Land use planners and managers are encouraged to incorporate climate warming into long-term planning.

Rapid long distance migration[edit]

In this theory, populations moved directly from the area unaffected by glacial movement to their present boundaries by rare, long distance, successful dispersals.[2] The movement of the population was dictated by rare events that occurred long distances from the parent population. These rare successes created their own parent populations, allowing for the subpopulation to disperse additional rare, long distance successes perpetuating the movement of the population. The distribution created by this kind of movement is described as a fat-tailed distribution. Though normal distribution, short distance expansion of each individual population still occurs, the overall expansion of the entire cluster of populations is determined by the long distance, rare events. This stretches the distribution due to increased weight at the extremes of the distribution. Long distance migration is usually modeled using integro-difference equations with slowly decreasing dispersal kernels.[2]

难度分析

1.从话题来看，本场考试考察的话题都是雅思常考话题。其中生物类话题任然很坚挺，上半年已经考过多篇生物类，同学们可以结合剑桥真题和真题还原加强对此类话题的熟悉，同时还要多看一些纪录片，加强背景知识的积累。第二类是心理类，此类话题比较抽象，需要有一定背景知识，备考时可以参考剑桥真题和真题还原相关题目。

2.从考试题型来看，涉及到摘要填空，是非无判断，段落细节信息匹配，单选。其中填空所占比重较大，每篇都有。建议烤鸭们在备考时一定要注意加强训练。需要熟练运用课上讲解的方法，达到事半功倍的效果。