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2014年11月8日托福阅读机经

2015-04-02 10:34:00 | 编辑: 无 | 有430人参与 | 来自: 匿名

以下是环球托福小编为你整理的2014年11月8日托福阅读机经,希望对各位考生有所帮助。

考试日期:2014118
Reading Passage 1
Title:生命组成元素
Question types:
文章内容回顾:主题:生命科学类话题
讲生命组成元素,element有九十多种,life element包括25种;然后讲了一下heavy element和氢、氦占元素的百分比,古老星球的heavy element百分比很低;地球生物最重要的元素是碳,其他星球具有生命所需的元素,所以可能有生命存在,并且可以based on碳或者硅或者其他元素;atmosphere和liquid必须存在,有利于元素相互反应,形成生命。  
难度分析:生命科学话题可谓是考生比较熟悉的一类,做题中经常会碰见类似话题。考试中要注意把握因果关系以及实验例子的目的和影响。
相关背景内容:A biosignature is any substance – such as an element, isotope, molecule, or phenomenon – that provides scientific evidence of past or present life. Measurable attributes of life include its complex physical and chemical structures and also its utilization of free energy and the production of biomass and wastes. Due to its unique characteristics, a biosignature can be interpreted as having been produced by living organisms; however, it is important that they not be considered definitive because there is no way of knowing in advance which ones are universal to life and which ones are unique to the peculiar circumstances of life on Earth.
The ancient record on Earth provides an opportunity to see what geochemical signatures are produced by microbial life and how these signatures are preserved over geologic time. Some related disciplines such as geochemistry, geobiology, and geomicrobiology often use biosignatures to determine if living organisms are or were present in a sample. These possible biosignatures include: (a) microfossils and stromatolites; (b) molecular structures (biomarkers) and isotopic compositions of carbon, nitrogen and hydrogen in organic matter; (c) multiple sulfur and oxygen isotope ratios of minerals; and (d) abundance relationships and isotopic compositions of redox sensitive metals (e.g., Fe, Mo, Cr, and rare earth elements).

For example, the particular fatty acids measured in a sample can indicate which types of bacteria and archaea live in that environment. Another example are the long-chain fatty alcohols with more than 23 atoms that are produced by planktonic bacteria. When used in this sense, geochemists often prefer the term biomarker. An other example is the presence of straight-chain lipids in the form of alkanes, alcohols an fatty acids with 20-36 carbon atoms in soils or sediments. Peat deposits are an indication of originating from the epicuticular wax of higher plants.

Life processes may produce a range of biosignatures such as nucleic acids, lipids, proteins, amino acids, kerogen-like material and various morphological features that are detectable in rocks and sediments.[8] Microbes often interact with geochemical processes, leaving features in the rock record indicative of biosignatures. For example, bacterial micrometer-sized pores in carbonate rocks resemble inclusions under transmitted light, but have distinct size, shapes and patterns (swirling or dendritic) and are distributed differently from common fluid inclusions.A potential biosignature is a phenomenon that may have been produced by life, but for which alternate abiotic origins may also be possible.
Reading Passage 2
Title:美国五大湖
Question types:
文章内容回顾:主题:历史文明类话题
讲美国五大湖地区的lumber,在十九世纪开始产业化,技术的发展使木材可以搬运到全国各地,stream水运木材,有一个啥技术可以控制水运的方向,使运输更快速;还有一个是在dry冬天,freeze减少摩擦力,解决冬天木材很难运的问题,可以运很重的木材了;另外就是铁路运输。
难度分析:历史考古类话题,考生要多熟悉世界古代文明和早起美国文明。首先要把握时间发展的时间线索,以及各个事件之间的逻辑关系。注意整篇文章中事件的冲突与发展变化。
相关背景内容:The Great Lakes (sometimes, Laurentian Great Lakes) or the Great Lakes of North America are a series of interconnected freshwater lakes located in northeastern North America, on the Canada–United States border, which connect to the Atlantic Ocean through the Saint Lawrence River. Consisting of Lakes Superior, Michigan, Huron (or Michigan–Huron), Erie, and Ontario, they form the largest group of freshwater lakes on Earth, containing 21% of the world's surface fresh water by volume. The total surface is 94,250 square miles (244,106 km2), and the total volume (measured at the low water datum) is 5,439 cubic miles (22,671 km3). Due to their sea-like characteristics: rolling waves, sustained winds, strong currents, great depths, and distant horizons, the five Great Lakes have also long been referred to as inland seas. Lake Superior is the largest continental lake in the world by area, and Lake Michigan is the largest lake that is entirely within one country.

The Great Lakes began to form at the end of the last glacial period around 10,000 years ago, as retreating ice sheets carved basins into the land and they became filled with meltwater.The lakes have been a major highway for transportation, migration and trade, and they are home to a large number of aquatic species. Many invasive species have been introduced due to trade, and some threaten the region's biodiversity.
Reading Passage 3
Title:megafauna
Question types:
文章内容回顾:主题:生物类话题
megafauna灭绝的问题,科学家提出是人类kill的,解释了一下为什么climate不会是灭绝的原因:很久之前有一次climate变化但没导致m灭绝,这次climate变化也不会导致灭绝。又提出m的灭绝正好与人类出现的时间一致,于是有两个人做了个模型,测出小部分人类在about 300年是可以猎杀m导致m灭绝的,有个人同意这个观点,并指出在人类活动的地方发现remains。但是只有很少的remains被发现,最后又跳出一个人,说在新西兰有种大鸟因为人类活动灭绝了,它的remains却被大量发现,从而进行反驳。
难度分析:生物类话题中的生物多样性是托福中一个很经典的话题,考生应主要注意分辨各种形成原因之间的区别以及各自的特点。
相关背景内容:In terrestrial zoology, megafauna (Ancient Greek megas "large" + New Latin fauna "animal") are large or giant animals. The most common thresholds used are 45 kilograms (100 lb) or 100 kilograms (220 lb).This thus includes many species not popularly thought of as overly large, such as white-tailed deer, red kangaroo, and humans.

In practice, the most common usage encountered in academic and popular writing describes land animals roughly larger than a human that are not (solely) domesticated. The term is especially associated with the Pleistocene megafauna — the land animals often larger than modern counterparts considered archetypical of the last ice age, such as mammoths, the majority of which in northern Eurasia, the Americas and Australia became extinct as recently as 10,000–40,000 years ago.[4] It is also commonly used for the largest extant wild land animals, especially elephants, giraffes, hippopotamuses, rhinoceroses, and large bovines. Megafauna may be subcategorized by their trophic position into megaherbivores (e.g., elk), megacarnivores (e.g., lions), and, more rarely, megaomnivores (e.g., bears).

Other common uses are for giant aquatic species, especially whales, any larger wild or domesticated land animals such as larger antelope and cattle, as well as numerous dinosaurs and other extinct giant reptilians.

The term is also sometimes applied to animals (usually extinct) of great size relative to a more common or surviving type of the animal, for example the 1 m (3 ft) dragonflies of the Carboniferous period.

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