考试日期：

2013年8月24日

Reading Passage 1

Title:

Organic Farming & Chemical Fertilizer

Question types:

Matching（人名&理论）;

True/False/Not Given;

Summary;

文章内容回顾

2010年8月14日旧题。全文围绕有机农业和传统农业展开话题，有人支持技术（即化肥）提高产量，有人支持有机农业（生态肥）。作者认为除了这两个，还有第三条路，就是智能农业。分别讲了chemical fertilizer和organic farming各自的优缺点，然后提出未来的intelligent farming。

相关英文原文阅读

Organic farming methods combine scientific knowledge of ecology and modern technology with traditional farming practices based on naturally occurring biological processes. Organic farming methods are studied in the field of agroecology. While conventional agriculture uses synthetic pesticides and water-soluble synthetically purified fertilizers, organic farmers are restricted by regulations to using natural pesticides and fertilizers. The principal methods of organic farming include crop rotation, green manures and compost, biological pest control, and mechanical cultivation. These measures use the natural environment to enhance agricultural productivity: legumes are planted to fix nitrogen into the soil, natural insect predators are encouraged, crops are rotated to confuse pests and renew soil, and natural materials such as potassium bicarbonate and mulches are used to control disease and weeds. Hardier plants are generated through plant breeding rather than genetic engineering.

While organic is fundamentally different from conventional because of the use of carbon based fertilizers compared with highly soluble synthetic based fertilizers and biological pest control instead of synthetic pesticides, organic farming and large-scale conventional farming are not entirely mutually exclusive. Many of the methods developed for organic agriculture have been borrowed by more conventional agriculture. For example, Integrated Pest Management is a multifaceted strategy that uses various organic methods of pest control whenever possible, but in conventional farming could include synthetic pesticides only as a last resort.

Crop diversity

Crop diversity is a distinctive characteristic of organic farming. Conventional farming focuses on mass production of one crop in one location, a practice called monoculture. The science of agroecology has revealed the benits of polyculture (multiple crops in the same space), which is often employed in organic farming. Planting a variety of vegetable crops supports a wider range of benicial insects, soil microorganisms, and other factors that add up to overall farm health. Crop diversity helps environments thrive and protect species from going extinct.

Soil management

Organic farming relies heavily on the natural breakdown of organic matter, using techniques like green manure and composting, to replace nutrients taken from the soil by previous crops. This biological process, driven by microorganisms such as mycorrhiza, allows the natural production of nutrients in the soil throughout the growing season, and has been rerred to as feeding the soil to feed the plant. Organic farming uses a variety of methods to improve soil fertility, including crop rotation, cover cropping, reduced tillage, and application of compost. By reducing tillage, soil is not inverted and exposed to air; less carbon is lost to the atmosphere resulting in more soil organic carbon. This has an added benit of carbon sequestration which can reduce green house gases and aid in reversing climate change.

Plants need nitrogen, phosphorus, and potassium, as well as micronutrients and symbiotic relationships with fungi and other organisms to flourish, but getting enough nitrogen, and particularly synchronization so that plants get enough nitrogen at the right time (when plants need it most), is a challenge for organic farmers. Crop rotation and green manure ("cover crops") help to provide nitrogen through legumes (more precisely, the Fabaceae family) which fix nitrogen from the atmosphere through symbiosis with rhizobial bacteria. Intercropping, which is sometimes used for insect and disease control, can also increase soil nutrients, but the competition between the legume and the crop can be problematic and wider spacing between crop rows is required. Crop residues can be ploughed back into the soil, and different plants leave different amounts of nitrogen, potentially aiding synchronization. Organic farmers also use animal manure, certain processed fertilizers such as seed meal and various mineral powders such as rock phosphate and greensand, a naturally occurring form of potash which provides potassium. Together these methods help to control erosion. In some cases pH may need to be amended. Natural pH amendments include lime and sulfur, but in the U.S. some compounds such as iron sulfate, aluminum sulfate, magnesium sulfate, and soluble boron products are allowed in organic farming.

Mixed farms with both livestock and crops can operate as ley farms, whereby the land gathers fertility through growing nitrogen-fixing forage grasses such as white clover or alfalfa and grows cash crops or cereals when fertility is established. Farms without livestock ("stockless") may find it more difficult to maintain soil fertility, and may rely more on external inputs such as imported manure as well as grain legumes and green manures, although grain legumes may fix limited nitrogen because they are harvested. Horticultural farms growing fruits and vegetables which operate in protected conditions are often even more reliant upon external inputs.

Biological research on soil and soil organisms has proven benicial to organic farming. Varieties of bacteria and fungi break down chemicals, plant matter and animal waste into productive soil nutrients. In turn, they produce benits of healthier yields and more productive soil for future crops. Fields with less or no manure display significantly lower yields, due to decreased soil microbe community, providing a healthier, more arable soil system.

题型难度分析

人名观点Matching题属于简单题型，定位非常容易。而是非无及填空也是常考题型之一，掌握相应技巧，难度不大。

题型技巧分析

Matching（人名&观 点）在近期的雅思阅读考试中出现的次数比较多。做这一题型，首先要明确它的题干是有序还是无序的（人名出现在题干中一般为有序）。其次要注意解题的顺序， 若是有序型的，则可按人名在文中出现的顺序解题，若是无序型的，按人名出现次数从少到多解题。在解题时，当定位到某一人名后，要特别留意此人所说的话（即 引号中的内容），而这一人名后附加的一长串头衔，则可省略不读。

剑桥雅思推荐原文练习

剑7 Test 2 Passage 2 The True Cost of Food

Reading Passage 2

Title:

昆虫中的等级制度问题

Question types:

List of Headings;

多选题；

句子填空；

文章内容回顾

谈及动物社会关系，比较bumblebee和queen wasp以及worker bee的等级和分工问题。

相关英文原文阅读

There are many more species of primitively eusocial bees than highly eusocial bees, but they have rarely been studied. The biology of most such species is almost completely unknown. The vast majority are in the family Halictidae, or "sweat bees". Colonies are typically small, with a dozen or fewer workers, on average. The only physical difference between queens and workers is average size, if they differ at all. Most species have a single season colony cycle, even in the tropics, and only mated females (future queens, or "gynes") hibernate (called diapause). A few species have long active seasons and attain colony sizes in the hundreds. The orchid bees include a number of primitively eusocial species with similar biology. Certain species of allodapine bees (relatives of carpenter bees) also have primitively eusocial colonies, with unusual levels of interaction between the adult bees and the developing brood. This is "progressive provisioning"; a larva&aposs food is supplied gradually as it develops. This system is also seen in honey bees and some bumblebees.

Highly eusocial bees live in colonies. Each colony has a single queen, many workers and, at certain stages in the colony cycle, drones. When humans provide the nest, it is called a hive. Honey bee hives can contain up to 40,000 bees at their annual peak, which occurs in the spring, but usually have fewer.

Bumblebees

Bumblebees (Bombus terrestris, Bombus pratorum, et al.) are eusocial in a manner quite similar to the eusocial Vespidae such as hornets. The queen initiates a nest on her own (unlike queens of honey bees and stingless bees which start nests via swarms in the company of a large worker force). Bumblebee colonies typically have from 50 to 200 bees at peak population, which occurs in mid to late summer. Nest architecture is simple, limited by the size of the nest cavity (pre-existing), and colonies are rarely perennial. Bumblebee queens sometimes seek winter safety in honey bee hives, where they are sometimes found dead in the spring by beekeepers, presumably stung to death by the honey bees. It is unknown whether any survive winter in such an environment.

Bumblebees are one of the more important wild pollinators, but have declined significantly in recent decades. In the UK, 2 species have become nationally extinct during the last 75 years while others have been placed on the UK Biodiversity Action Plan as priority species in recognition of the need for conservation action. In 2006 a new charity, the Bumblebee Conservation Trust, was established to coordinate forts to conserve remaining populations through conservation and education. In 2011, the International Union for the Conservation of Nature set up the Bumblebee Specialist Group to review the threat status of all bumblebee species world-wide using the IUCN Red List criteria.

Stingless bees

Stingless bees are very diverse in behavior, but all are highly eusocial. They practise mass provisioning, complex nest architecture, and perennial colonies.

Honey bees

The true honey bees (genus Apis) have arguably the most complex social behavior among the bees. The European (or Western) honey bee, Apis mellifera, is the best known bee species and one of the best known of all insects.

Africanized honey bee

Africanized bees, also called killer bees, are a hybrid strain of Apis mellifera derived from experiments by Warwick Estevam Kerr to cross European and African honey bees. Several queen bees escaped from his laboratory in South America and have spread throughout the Americas. Africanized honey bees are more densive than European honey bees.

题型难度分析

本篇文章属于自然科学类的文章，生词较多，且部分题目定位不容易找到，整体来说难度偏高。

题型技巧分析

标题配对题（List of headings）是雅思阅读中的一种重要题型，要求给段落找小标题。它一般位于文章之前，由两部分组成：一部分是选项，另一部分是段落编号，要求给各个段落找到与它对应的选项，即表达了该段中心思想的选项，有时还会举一个例子。当然，例子中的选项是不会作为答案的。

解题思路：

1. 将例子所对应的选项及段落标号划去

2. 划出选项中的关键词及概念性名词

3. 浏览文章，抓住各段的主题句和核心词（尤其是反复出现的核心词），重点关注段落首句、第二句与末句

4. 与段落主题句同义或包含段落核心词的选项为正确答案

剑桥雅思推荐原文练习

剑7 Test 3 Passage 1 Ant Intelligence

Reading Passage 3

Title:

恒星和行星

Question types:

段落细节信息定位题；

是非无判断；

句子填空；

文章内容回顾

关于stars的理论和研究，以及planet without sun等。

相关英文原文阅读

A star is a massive, luminous sphere of plasma held together by its own gravity. Our nearest star is the Sun, which is the source of most of the energy on Earth. Some other stars are visible from Earth during the night when they are not obscured by clouds or other atmospheric phenomena, appearing as a multitude of fixed luminous points due to their immense distance. Historically, the most prominent stars were grouped into constellations and asterisms, and the brightest stars gained proper names. Extensive catalogues of stars have been assembled by astronomers, which provide standardized star designations.

For at least a portion of its life, a star shines due to thermonuclear fusion of hydrogen into helium in its core, releasing energy that traverses the star&aposs interior and then radiates into outer space. Once the hydrogen in the core of a star is nearly exhausted, almost all naturally occurring elements heavier than helium are created by stellar nucleosynthesis during the star&aposs lifetime and, for some stars, by supernova nucleosynthesis when it explodes. Near the end of its life, a star can also contain degenerate matter. Astronomers can determine the mass, age, metallicity (chemical composition), and many other properties of a star by observing its motion through space, luminosity, and spectrum respectively. The total mass of a star is the principal determinant of its evolution and eventual fate. Other characteristics of a star, including diameter and temperature, change over its life, while the star&aposs environment affects its rotation and movement. A plot of the temperature of many stars against their luminosities, known as a Hertzsprung–Russell diagram (H–R diagram), allows the age and evolutionary state of a star to be determined.

A star&aposs life begins with the gravitational collapse of a gaseous nebula of material composed primarily of hydrogen, along with helium and trace amounts of heavier elements. Once the stellar core is sufficiently dense, hydrogen becomes steadily converted into helium through nuclear fusion, releasing energy in the process. The remainder of the star&aposs interior carries energy away from the core through a combination of radiative and convective processes. The star&aposs internal pressure prevents it from collapsing further under its own gravity. Once the hydrogen fuel at the core is exhausted, a star with at least 0.4 times the mass of the Sun expands to become a red giant, in some cases fusing heavier elements at the core or in shells around the core. The star then evolves into a degenerate form, recycling a portion of its matter into the interstellar environment, where it will form a new generation of stars with a higher proportion of heavy elements. Meanwhile, the core becomes a stellar remnant: a white dwarf, a neutron star, or (if it is sufficiently massive) a black hole.

Binary and multi-star systems consist of two or more stars that are gravitationally bound, and generally move around each other in stable orbits. When two such stars have a relatively close orbit, their gravitational interaction can have a significant impact on their evolution. Stars can form part of a much larger gravitationally bound structure, such as a star cluster or a galaxy.

题型难度分析

本篇文章共三种题型，基本都为细节题，总体难度相对而言较高。

题型技巧分析

是非无判断题几乎是每次阅读考试必考的题型，且题量较大。所以对于这一常考题型，同学们一定要熟知其解题技巧。特别要区分清楚No和Not Given在判断标准上的差异。而对于一些考题中经常出现的经典考点，我们也要能够识别。

1. 数字（但年份一般不作为考点）

2. 比较（常见答案为NOT GIVEN）

3. 增加&减少（increase/ rise/ grow/ climb/ accelerate; decrease/ decline/ reduce/ crash）

4. 超过（over/ more than/ exceed/ excess）

5. 绝对化（all/ fully/ must/ only/ unique/ never）

6. 逻辑关系

剑桥雅思推荐原文练习

剑9 Test 2 Passage 2 Venus in Transit

考试趋势分析和备考指导：

1. 此次考试整体难度比较高，考察文章多为自然科学类，学生往往会因为生词多，看不懂，做题愈加急躁，导致心理压力过大，错误率升高。要在平时多积累一些科学知识背景，并学会有效规避生词的方法。

2. 三篇文章之前都考过相同或相似类型的，考生应多多关注考题回顾，注意重复率较高的话题文章。

3. 考试题型并没有太大新意，仍然保持热门类题型（填空与是非无）居多，考生应多熟悉这些热门题型的解题方法和技巧，在考场上灵活运用。