2014年7月12日托福阅读真题P2+题目+答案：How Soil is Formed

2014年7月12日托福阅读真题P2+题目+答案：How Soil is Formed

Soil formation is a dynamic process that takes place in different environments. It is strongly influenced by the parent material, climate (largely vegetation and temperature and water exchanges), topography (the elevations, depressions, directions and angles of slopes, and other surface features of the landscape), and time.

The parent material is the unconsolidated mass on which soil formation takes place. This material may or may not be derived from the on-site geological substrate or bedrock on which it rests. Parent materials can be transported by wind, water, glaciers, and gravity and deposited on top of bedrock. Because of the diversity of materials involved, soils derived from transported parent materials are commonly more fertile than soils from parent materials derived in place. Whatever the parent material, whether derived in place from bedrock or from transported material, it ultimately comes from geological materials, such as igneous, sedimentary, and metamorphic rocks, and the composition of the rocks largely determines the chemical composition of the soil.

1. According to paragraph 2, which of the following is true about parent material found at a given site?

A.It was most likely deposited there by glaciers rather than by wind and water.

B.It is formed and consolidated entirely from the bedrock on which it rests.

C.It can vary in its richness and fertility according to where it originated.

D.The speed with which it is transported determines its location.

答案：C

2. Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.

A.Transported parent materials, parent materials derived in place from bedrock,and various kinds of rocks all contribute to the composition of a soil.

B.The chemical composition of a soil is ultimately determined by the geological materials from which it forms, regardless of where or how the parent material originates.

C.The parent material from which a soil is formed ultimately comes from igneous,sedimentary, and metamorphic rocks.

D.The composition of the geological materials from which the parent material was originally derived can be determined by studying the chemical composition of the soil.

答案：B

Climate is most influential in determining the nature and intensity of weathering and the type of vegetation that further affects soil formation. The soil material experiences daily and seasonal variations in heating and cooling. Open surfaces exposed to thermal radiation undergo the greatest daily fluctuations in heating and cooling, soils covered with vegetation the least. Hill slopes facing the sun absorb more heat than those facing away from the sun. Radiant energy has a pronounced effect on the moisture regime, especially the evaporative process and dryness. Temperature can stimulate or inhibit biogeochemical reactions in soil material.

3. The word "further" in the passage is closest in meaning to

A.as a result

B.additionally

C.potentially

D.eventually

答案：B

4. The word "fluctuations" in the passage is closest in meaning to

A.extremes

B.increases

C.variations

D.effects

答案：C

5. The word "inhibit" in the passage is closest in meaning to

A.initiate

B.remove

C.slow down

D.damage

答案：C

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