2013年10月27日托福阅读真题解析
经济学英语第一篇
TOPIC 地下水渗透层
讲地下水上面有一层渗透层unsaturated V? layer。开头有附图。这一层分为三部分，分别是soil，subsoil和fringe（毛细管layer）。分别介绍这3部分。前两层都是水的缓冲区域，第三层是被水浸湿的。还讲了它们的构造以及groundwater的循环，水有三个途径：形成地下水、汇入河流和蒸发入大气。
解析：本文话题属地质学内容，结构属描述说明类，结合分类方式阐述。仅在暗恋最心酸的瞬间>粉皮子TPO中就有两篇文章即以groundwater组织培养技术也就是地下水作为标题，说明其考察频率较高。同学普遍反馈本文较为简单，应该并未就各部分内容进行过多过复杂的描述。
Vado Zone
The vado zone, also termed the unsaturated zone, is the part of Earth between the land s
urface and the top of the phreatic the position at which the groundwater (the water in the soil's pores) is at atmospheric pressure ("vado" is from the Latin for "shallow"). Hence the vado zone extends from the top of the ground surface to the water table. Water in the vado zone has a pressure head less than atmospheric pressure, and is retained by a combination of adhesion (funiculary groundwater), and capillary action (capillary groundwater). If the vado zone envelops soil, the water contained therein is termed soil moisture. In fine grained soils, capillary action can cau the pores of the soil to be fully saturated above the water table at a pressure less than atmospheric. In such soils, therefore, the unsaturated zone is the upper ction of the vado zone and not identical to it.
Movement of water within the vado zone is studied within soil physics and hydrology, particularly hydrogeology, and is of importance to agriculture, contaminant transport, and flood control. The Richards equation is often ud to mathematically describe the flow of water, which is bad partially on Darcy's law. Groundwater recharge, which is an important process that refills aquifers, generally occurs through the vado zone from pre
cipitation.
In speleology, cave passages formed in the vado zone tend to be canyon-like in shape, as the water dissolves bedrock on the floor of the passage. Passages created in completely water-filled conditions are called phreatic passages and tend to be circular in cross-ction.
Capillary fringe
The capillary fringe is the subsurface layer in which groundwater eps up from a water table by capillary action to fill pores. Pores at the ba of the capillary fringe are filled with water due to tension saturation. This saturated portion of the capillary fringe is less than total capillary ri becau of the prence of a mix in pore size. If pore size is small and relatively uniform, it is possible that soils can be completely saturated with water for veral feet above the water table. Alternately, the saturated portion will extend only a few inches above the water table when pore size is large. Capillary action supports a vado zone above the saturated ba within which water content decreas with distanc
e above the water table. In soils with a wide range in pore size, the unsaturated zone can be veral times thicker than the saturated zone.
Some workers restrict their definition of the capillary fringe only to the tension-saturated ba portion and exclude it wholly from the vado zone. This is more common among workers addressing solute transport and water flow. Others define the capillary fringe as including both the tension-saturated and unsaturated portions. This is the preferred definition among workers dealing with the remediation of salt affected soils as well as tho dealing with the vapor pha of soil process and bioremediation. It is not uncommon to e the capillary fringe treated as a boundary condition parating the water table from the unsaturated zone, without defining it as a significant part of either. Also it is the space between the surface layer and the aquifer.
Soil Horizon
Soil generally consists of visually and texturally distinct layers, which can be summarized as follows from top to bottom:
O) Organic matter: Litter layer of plant residues in relatively undecompod form.
A) Surface soil: Layer of mineral soil with most organic matter accumulation and soil life. This layer eluviates (is depleted of) iron, clay, aluminum, organic compounds, and other soluble constituents. When eluviation is pronounced, a lighter colored "E" subsurface soil horizon is apparent at the ba of the "A" horizon. A-horizons may also be the result of a combination of soil bioturbation and surface process that winnow fine particles from biologically mounded topsoil. In this ca, the A-horizon is regarded as a "biomantle".
B) Subsoil: This layer accumulates iron, clay, aluminum and organic compounds, a process referred to as illuviation.质心系
C) Parent rock: Layer of large unbroken rocks. This layer may accumulate the more soluble compounds.
R) Bedrock: R horizons denote the layer of partially weathered bedrock at the ba of the soil profile. Unlike the above layers, R horizons largely compri continuous mass (as
oppod to boulders) of hard rock that cannot be excavated by hand. Soils formed in situ will exhibit strong similarities to this bedrock layer.
第二篇
燕麦吃法
TOPIC Moon Surface
讲月球表面，出现clay，各个科学家不断证明是陨石撞击形成，而不是火山，讲了证明过程。
解析：本文话题属天文学话题，结构应属问题解决类。本文普遍反映较难，同学回忆较少，根据分析，主要是证明月球表面由陨石撞击造成这一点上写得很可能比较复杂。面对较难文章，尤其如果出现在考试时的第一或者第二篇，千万不要过多的耗费时间，一定要控制好时间分配，不要影响最后一篇文章的作答，导致较难文章正确率低并且其他文章也没做完的窘境。TPO中与之类似的文章为TPO25的The Surface Of Mars创业项目排行榜火星表面，里面也分别谈及了火星表面的陨石坑和火山。
Lunar craters
投标文件完整范本免费
Scientific opinion as to the origin of craters swung back and forth over the ensuing centuries. The competing theories were (a) volcanic eruptions blasting holes in the Moon, (b) meteoric impact, (c) a theory known as the Welteislehre developed in Germany between the two World Wars which suggested glacial action creating the craters.
