高考英语阅读急救箱（47）：土壤

今日学习

小编在此为大家附上高考英语阅读的高频词汇，同时也会增加阅读难度哦，一起来看看吧。

小方法

101. organ n. 器官,风琴
102. excess n. 过分,过量,过剩
103. expel v. 驱逐,开除,赶出
104. expend v. 消费
105. expenditure n. 支出,消费；经费
106. expense n. 开销,费用
107. expensive a. 花钱多的；价格高贵的
108. expand v. 扩大,扩张；展开,膨胀
109. expansion n. 扩大,扩充；发展,膨胀
110. private a. 私人的,个人的

小小练习

Have you ever noticed the colour of the water in a river or stream after a heavy rainfall? What do you think caused this change in colour? It is soil that has been washed into the river from the riverbank or from the nearby fields.

Components of Soil

Soil is made up of a number of layers (层) , each having its own distinctive colour and texture. The upper layer is known as the litter. It acts like a blanket，limiting temperature changes and reducing water loss. The topsoil layer is made up of small particles of rock mixed with rotten plant and animal matter called humus (腐殖质), which is black and gives the topsoil its dark colour. This layer is usually rich in nutrients, oxygen, and water. Below the topsoil is the subsoil, a layer that contains more stones mixed with only small amounts of organic matter. This layer is lighter in colour because of the lack of humus. Beneath the soil lies a layer of bedrock.

Soil forms from the bottom up. Over time bedrock is attacked by rain, wind, frost, and snow. It is gradually broken down into smaller particles in a process called weathering. Plants begin to grow，and rotten materials enrich the topsoil. Most of the soil in Eastern Canada ，for example ，was formed from weathered rock that was exposed when the ice disappeared 12,000 years ago.

Water Beneath the Soil

Surface water collects and flows above the ground in lakes ，ponds, and rivers. Once in the soil or rock, it is called groundwater. Gravity pulls groundwater through the soil in a process called percolation(渗透). Eventually the water reaches a layer called the water table. Under this is bedrock through which water cannot percolate.

As water percolates downward, it dissolves organic matter and minerals from the soil and carries them to deeper layers. This causes a serious problem because plants require these nutrients for growth.

Soil pH

Soil can be acidic, neutral, or basic. The pH of the soil is determined by the nature of the rock from which it was formed，and by the nature of the plants that grow and rot in it.The acidity of rain and snow can lower the pH of the groundwater that enters the soil. By burning fossil fuels such as coal ，oil and gasoline，humans have been contributing to higher levels of acidity in many soils. When fossil fuels are burned，gases are released into the air and then fall back to earth as acid rain. Acid soil increases the problem of carrying nutrients to lower soil levels. As nutrients are removed，soil is less fertile. Plants grow more slowly in acidic soil，and also become easily attacked by diseases.

1、The layer of soil that provides necessary nutrients for plant growth is called________.
A. litter           B. topsoil        C. humus       D. subsoil

2、According to the text, which of the following is NOT true?

A. Soil forms from weathered rock on the earth surface.

B. The deeper layer of soil is darker in colour than the surface soil.

C. Air pollution is partially responsible for acid soil.

D. Groundwater tends to carry away nutrients for plant growth.

3、We can infer from the passage that the water table lies________.

A. between the topsoil layer and the subsoil layer

B. in the subsoil layer above bedrock

C. between the subsoil layer and bedrock

D. in the bedrock layer beneath the subsoil

4、The underlined word “dissolve” is used to express the idea that organic matter and minerals from soil are________.

A. rushed away into the river                                             B. cleaned and purified by water

C. destroyed and carried away by water                              D. mixed with water and become part of it

语篇解读
本文是一篇科普文，介绍了土壤的构成与土壤的pH对于植物生长的影响。

做题方法
1. 通读全文，领悟大意，理解文章结构层次及细节。
2. 选用排除法排除不符合原文细节的选项，剩下的就是要选择的最佳答案。
3. 利用文章明确表示的内容进行推理。
 
文章大意
土壤是由许多层(层),每个都有自己的独特的颜色和纹理。上层通常称为垃圾。它就像一条毯子,限制温度变化和减少水耗。表层土的层是由小颗粒的岩石混合着腐烂的植物和动物的物质称为腐殖质(腐殖质),它是黑色的,给出了其深色表层土。这一层通常是富含营养物质、氧气和水。以下是下层土壤的表层土,一层,包含更多的石头混合只有少量的有机物质。这一层是打火机颜色因为缺乏腐殖质。土壤下面是一层基岩。
表面水收集和流动地上湖泊、池塘、河流。一旦进入土壤或岩石,它被称为地下水。地心引力的地下水通过土壤这一过程被称为渗流(渗透)。最终水位达到层称为水位。这是通过下基岩水不能渗出。作为水渗流向下,它溶解有机物和矿物质从土壤和携带他们更深的层次。这导致一个严重的问题,因为这些营养的植物需要为增长。
土壤可以酸性、中性或基本的本性。土壤的pH值是由岩石的性质,它可以形成,自然植物,生长和腐烂。雨和雪的酸性可以降低pH值的地下水,进入土壤。通过燃烧化石燃料如煤炭、石油和汽油,人类已经导致更高水平的酸度在许多土壤。当化石燃料被焚烧,气体被释放到空气中然后回到地球作为酸雨。酸性土壤增加问题的运输营养降低土壤水平。作为营养是移除,土壤贫瘠。植物生长在酸性土壤更慢,也变得容易遭到疾病。

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