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. [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。 1．The layer of soil that provides necessary nutrients for plant growth is called________. A. litter B. topsoil C. humus D. subsoil [解析] 考查细节理解。根据文章第二段中的“The topsoil layer is made up of small particles of rock mixed with rotten plant...which is black and gives the topsoil its dark colour.This layer is usually rich in nutrients”可知给植物提供必要营养的土层是topsoil layer。 [答案] B 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. [解析] 考查细节判断。根据文章第二段中的“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”可知，并不是土层深，它的颜色就深。 [答案] B 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 [解析] 考查细节理解。根据文章第四段中的“Eventually the water reaches a layer called the water table.Under this is bedrock through which water cannot percolate”可知water table是位于bedrock之上的一个土层，它是独立存在的不属于其他层，因此选项C正确。 [答案] C 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 [解析] 考查词义猜测。根据本句中的“...and carries them to deeper layers”可知营养物质是在被水溶解之后才被带到更深的土层中去的。 [答案] D
The latest research suggests that the key factor separating geniuses from the merely accomplished is not IQ, a generally bad predictor of success.Instead, it’ s purposeful practice.Top performers spend more hours practising their craft. If you wanted to picture how a typical genius might develop, you’ d take a girl who possessed a slightly above average language ability. It wouldn’ t have to be a big talent, just enough so that she might gain some sense of distinction. Then you would want her to meet, say, a novelist, who coincidentally shared some similar qualities. Maybe the writer was from the same town, had the same family background, or, shared the same birthday. This contact would give the girl a vision of her future self.It would give her some idea of a fascinating circle she might someday join.It would also help if one of her parents died when she was 12, giving her a strong sense of insecurity and fuelling a desperate need for success. Armed with this ambition, she would read novels and life stories of writers without end. This would give her a primary knowledge of her field.She’d be able to see new writing in deeper ways and quickly understand its inner workings. Then she would practise writing. Her practice would be slow, painstaking and errorfocused. By practising in this way，she delays the automatizing process. Her mind wants to turn conscious, newly learned skills into unconscious, automatically performed skills. By practising slowly, by breaking skills down into tiny parts and repeating, she forces the brain to internalize a better pattern of performance. Then she would find an adviser who would provide a constant stream
