托福阅读真题练习：土壤质地的文本+真题+答案

2017年11月08日14:26 来源：小站整理: 参与（0）阅读（15636）

摘要：托福阅读真题哪里有?大家平时备考托福阅读考试的时候都用的是哪些真题呢?除了官方真题Official的托福阅读真题以外，大家进行托福阅读的练习大多数可能都是根据老托资料或者是课外资料来练习了。那么到哪里去找到托福阅读真题来进行练习呢?

托福阅读如何进行备考?除了大量的托福词汇储备以外，大家可能最需要的就是托福阅读真题的练习。那么除了官方真题Official你还有哪些托福阅读真题进行练习呢?今天小编就为大家整理了托福阅读真题100篇：土壤质地的文本、题目以及答案，希望可以帮助到大家。

托福阅读100篇真题练习汇总：http://toefl.zhan.com/tfziliao63739.html

托福阅读文本：

The mineral particles found in soil range in size from microscopic clay particles to large boulders. The most abundant particles — sand, silt, and clay — are the focus of examination in studies of soil texture. Texture is the term used to describe the composite sizes of particles in a soil sample, typically several representative handfuls.

To measure soil texture, the sand, silt, and clay particles are sorted out by size and weight. The weights of each size are then expressed as a percentage of the sample weight. In the field, soil texture can be estimated by extracting a handful of soil and squeezing the damp soil into three basic shapes; (1) cast, a lump formed by squeezing a sample in a clenched fist; (2) thread, a pencil shape formed by rolling soil between the palms; and (3) ribbon, a flatfish shape formed by squeezing a small sample between the thumb and index finger. The behavioral characteristics of the soil when molded into each of these shapes, if they can be formed at all, provide the basis for a general textural classification. The behavior of the soil in the hand test is determined by the amount of clay in the sample. Clay particles are highly cohesive, and when dampened, behave as a plastic. Therefore the higher the clay content in a sample, the more refined and durable the shapes into which it can be molded.

Another method of determining soil texture involves the use of devices called sediment sieves,screens built with a specified mesh size. When the soil is filtered through a group of sieves, each with a different mesh size, the particles become grouped in corresponding size categories. Each category can be weighed to make a textural determination. Although sieves work well for silt, sand, and larger particles, they are not appropriate for clay particles. Clay is far too small to sieve accurately; therefore, in soils with a high proportion of clay, the fine particles are measured on the basis of their settling velocity when suspended in water. Since clays settle so slowly, they are easily segregated from sand and silt. The water can be drawn off and evaporated, leaving a residue of clay, which can be weighed.

托福阅读题目：

1. What does the passage mainly discuss?

(A) Characteristics of high quality soil

(B) Particles typically found in most soils

(D) Ways to determine the texture of soil

2. The author mentions "several representative handfuls" in line 4 in order to show

(A) the range of soil samples

(B) the process by which soil is weighed

(D) how small soil particles are weighted

3. The phrase "sorted out" in line 5 is closest in meaning to

(A) mixed

(B) replaced