2017年3月25托福答案解析考试真题

　　“托福”(TOEFL)这个词对当今的中国年轻人来说,并不陌生。现方便大家阅读，整理了3月25日托福答案解析。下面就是学习啦小编给大家整理的2017年3月25日托福考试答案解析，希望对你有用!

　　2017年3月25日托福听力真题答案及解析

　　Conversation 1

　　话题分类： student and employee

　　内容回忆： 学生问老师为什么我们学校没有去西班牙的交换计划，说自己朋友的大学就有西班牙留学的项目，老师说之前是有的，但是现在没有了，现在只有为期一年的出国留学计划。男生说一年的话就来不及完成别的必修课的学分了。老师说，如果申请留学计划的话还可以申请奖学金，男生很吃惊，问老师做交换生可以有学分吗?老师建议男生把西班牙学校的学习大纲发给她看看然后再决定能不能抵学分。

　　Conversation 2

　　话题分类 student and course advisor

　　内容回忆： 女生去意大利进行艺术交流学习，回来之后发现想选的课取消了。问老师怎么办，解决办法是选一门low level course。老师建议女生想好自己想要研究的课题，然后联系教授指导。之后学生还和老师进行了艺术方面的交流。

　　Lecture 1

　　学科分类：人类学

　　标题： sedentary lifestyle

　　内容回忆： 早期的人类是以打猎和采集为生的，但是后来人类开始了sedentary lifestyle。 这种定居对生活有利有弊。好处是人类可以获得更加稳定的食物来源，种植大量的农作物，但是也有缺点，例如相比狩猎和采集生活来说，定居生活的人类获得的食物的营养非常单一。另外，如果发生自燃灾害，很可能颗粒无收，生活受到威胁。最后，人们和牲畜生活在一起的聚居生活，很容易引发传染病。

　　Lecture 2

　　学科分类： Music History

　　标题： 巴洛克时期的音乐

　　内容回忆： 讲了巴洛克时期的音乐，受到了古希腊哲学家的影响。古希腊哲学家认为音乐可以塑造人的性格，还可以传递感情，巴洛克时期音乐的对比很强烈，还提到了两种不同的音乐模式，一种音乐混合了多种旋律，旋律之间相互有联系有彼此独立。另一种音乐只有一种旋律，但是这种旋律很适合音乐剧独白，因此这种形式通常出现在音乐剧中。

　　Lecture 3

　　学科分类： Geology

　　标题： Geothermal Energy地热能

　　内容回忆： 地热能是一种天然的热能，来自地球内部的熔岩，可以导致火山爆发和地震。通过地下水，地热可以被传送到离地面比较近的地方。熔岩会加热地下水，这些水最终会渗出地表。19世纪很多企业开始利用地热能，但是在此之后，越来越多的公司开始利用靠近地表的地热。为了监控地热能，科学家们想出了很多的办法，例如在黄石公园，研究者们利用高空探测器，通过测量温度来监控地热能。

　　Lecture 4

　　学科分类： Astronomy

　　标题： 行星探测

　　内容回忆： 通常人们认为适合生存的行星必须要有水，有生命，这种行星离恒心的距离一般是比较固定的。但是最新的研究发现这并不一定。有些行星是气体巨星，比地球大很多。有些行星距离恒星的距离太远了。后来还提到了K18星球，以及如何发现。教授说还有可能会发现类似的星球，而且会距离地球更近一些。

　　2017年3月25日托福阅读真题答案及解析

　　Passage One

　　学科分类：农业类

　　题目：Soil Fertilization

　　内容回忆： 真题Soil Fertilization

　　Fertilizers partially restore plant nutrients lost by erosion, crop harvesting, and leaching. Farmers can use either organic fertilizer from plant and animal materials or commercial inorganic fertilizer produced from various minerals. Three basic types of organic fertilizer are animal manure, green manure, and compost. Animal manure includes the waste matter of cattle, horses, poultry, and other farm animals. It improves soil structure, adds organic nitrogen, and stimulates beneficial soil bacteria and fungi.

　　Despite its effectiveness, the use of animal manure in the United States has decreased. There are three reasons for this: the replacement of most mixed animal-raising and crop-farming operations with separate operations for growing crops and raising animals, the high costs of transporting animal manure from feedlots near urban areas to distant rural crop-growing areas, and the replacement of horses and other draft animals that added manure to the soil with tractors and other motorized farm machinery.

　　Green manure is fresh or growing green vegetation plowed into the soil to increase the organic matter and humus (degraded organic matter) available to the next crop. Compost is a sweet-smelling, dark-brown, humuslike material that is rich in organic matter and soil nutrients. It is produced when microorganisms in soil (mostly fungi and aerobic bacteria) break down organic matter such as leaves, food wastes, paper, and wood in the presence of oxygen. Compost is a rich natural fertilizer and soil conditioner that aerates soil, improves its ability to retain water and nutrients, helps prevent erosion, and prevents nutrients from being wasted by being dumped in landfills. Compost is produced by piling up alternating layers of nitrogen-rich wastes (such as grass clippings, weeds, animal manure, and vegetable kitchen scraps), carbon-rich plant wastes (dead leaves, hay, straw, sawdust), and topsoil. Compost provides a home for microorganisms that help decompose plant and manure layers and reduces the amount of plant wastes taken to landfills and incinerators.

　　Another form of organic fertilizer is the spores of mushrooms, puffballs, and truffles. Rapidly growing and spreading mycorrhizae fungi in the spores attach to plant roots and help them take in moisture and nutrients from the soil. Unlike typical fertilizers that must be applied every few weeks, one application of mushroom fungi lasts all year and costs just pennies per plant. The fungi also produce a bigger root system, which makes plants more disease resistant.

　　Corn, tobacco, and cotton can deplete the topsoil of nutrients, especially nitrogen, if planted on the same land several years in a row. One way to reduce such losses is crop rotation. Farmers plant areas or strips with nutrient-depleting crops one year. In the next year they plant the same areas with legumes, whose root nodules add nitrogen to the soil. In addition to helping restore soil nutrients, this method reduces erosion by keeping the soil covered with vegetation and helps reduce crop losses to insects by presenting them with a changing target.

　　Today, many farmers rely on commercial inorganic fertilizers containing nitrogen (as ammonium ions, nitrate ions, or urea), phosphorus (as phosphate ions), and potassium (as potassium ions). Inorganic commercial fertilizers are easily transported, stored, and applied. Worldwide, their use increased about tenfold between 1950 and 1989 but declined by 12% between 1990 and 1999. Today, the additional food they help produce feeds one of every three people in the world, without them, world food output, would drop an estimated 40%.

　　Commercial inorganic fertilizers have some disadvantages, however. These include (1) not adding humus to the soil, (2) reducing the soil’s content of organic matter and thus its ability to hold water (unless animal manure and green manure are also added to the soil), (3) lowering the oxygen content of soil and keeping fertilizer from being taken up as efficiently, (4) typically supplying only two or three of the twenty or so nutrients needed by plants, and (5) releasing nitrous oxide, a greenhouse gas that can enhance global warming. The widespread use of commercial inorganic fertilizers, especially on sloped land near streams and lakes, also causes water pollution as nitrate and phosphate fertilizer nutrients are washed into nearby bodies of water. The resulting plant nutrient enrichment causes algae blooms that use up oxygen dissolved in the water, thereby killing fish.

　　Paragraph 1

　　Fertilizers partially restore plant nutrients lost by erosion, crop harvesting, and leaching. Farmers can use either organic fertilizer from plant and animal materials or commercial inorganic fertilizer produced from various minerals. Three basic types of organic fertilizer are animal manure, green manure, and compost. Animal manure includes the waste matter of cattle, horses, poultry, and other farm animals. It improves soil structure, adds organic nitrogen, and stimulates beneficial soil bacteria and fungi.

　　1、The word "beneficial" in the passage is closest in meaning to

　　necessary

　　helpful

　　several

　　hidden

　　Paragraph 2

　　Despite its effectiveness, the use of animal manure in the United States has decreased. There are three reasons for this: the replacement of most mixed animal-raising and crop-farming operations with separate operations for growing crops and raising animals, the high costs of transporting animal manure from feedlots near urban areas to distant rural crop-growing areas, and the replacement of horses and other draft animals that added manure to the soil with tractors and other motorized farm machinery.

　　2、According to paragraph 2, all of the following contributed to the decrease in the use of animal manure in the United States EXCEPT

　　changes in crop-farming and animal-raising operations

　　high transportation costs

　　the movement or large numbers of feedlots to distant rural areas

　　the introduction of motorized farm machinery

　　Paragraph 3

　　Green manure is fresh or growing green vegetation plowed into the soil to increase the organic matter and humus (degraded organic matter) available to the next crop. Compost is a sweet-smelling, dark-brown, humuslike material that is rich in organic matter and soil nutrients. It is produced when microorganisms in soil (mostly fungi and aerobic bacteria) break down organic matter such as leaves, food wastes, paper, and wood in the presence of oxygen. Compost is a rich natural fertilizer and soil conditioner that aerates soil, improves its ability to retain water and nutrients, helps prevent erosion, and prevents nutrients from being wasted by being dumped in landfills. Compost is produced by piling up alternating layers of nitrogen-rich wastes (such as grass clippings, weeds, animal manure, and vegetable kitchen scraps), carbon-rich plant wastes (dead leaves, hay, straw, sawdust), and topsoil. Compost provides a home for microorganisms that help decompose plant and manure layers and reduces the amount of plant wastes taken to landfills and incinerators.

　　3、According to paragraph 3, what is one advantage of using compost in raising crops?

　　It makes the soil easier to plow in preparation for planting.

　　Water and nutrients stay in the soil and enable plant growth.

　　The damage to soil from microorganisms is reduced.

　　Excess oxygen is removed from the soil.

　　4、According to paragraph 3, one important physical effect of compost is that it

　　adds an oxygen-rich layer to the layers rich in nitrogen and carbon

　　decreases the quantity of plant material that needs to be discarded

　　helps keep the same amount of moisture in each layer of soil

　　reduces the amount of fungi and aerobic bacteria in the pile

　　Paragraph 4

　　Another form of organic fertilizer is the spores of mushrooms, puffballs, and truffles.

　　Rapidly growing and spreading mycorrhizae fungi in the spores attach to plant roots and help them take in moisture and nutrients from the soil. Unlike typical fertilizers that must be applied every few weeks, one application of mushroom fungi lasts all year and costs just pennies per plant. The fungi also produce a bigger root system, which makes plants more disease resistant.

　　5、According to paragraph 4, each of the following is an advantage of using mushroom spores as fertilizer EXCEPT:

　　The cost of using mushroom spores is relatively low.

　　A single application of mushroom spores is enough for a whole year.

　　Mushroom fungi are nutrients that plants can take in easily.

　　Mushroom fungi help protect plants from disease.

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