托福阅读常考话题及练习题推荐五：地下水（2）

1 托福阅读常考话题：地下水练习题

Paragraph 1: Rainfall is not completely absent in desert areas, but it is highly variable. An annual rainfall of four inches is often used to define the limits of a desert. The impact of rainfall upon the surface water and groundwater resources of the desert is greatly influenced by landforms. Flats and depressions where water can collect are common features, but they make up only a small part of the landscape.

1. Which of the following statements about annual rainfall can be inferred from paragraph 1?

A. Flat desert areas receive more annual rainfall than desert areas with mountains.

B. Areas that receive more than four inches of rain per year are not considered deserts.

C. Many areas receive less than four inches of annual rainfall, but only a few are deserts.

D. Annual rainfall has no impact on the groundwater resources of desert areas.

Paragraph 2: Arid lands, surprisingly, contain some of the world’s largest river systems, such as the Murray-Darling in Australia, the Rio Grande in North America, the Indus in Asia, and the Nile in Africa. These rivers and river systems are known as "exogenous" because their sources lie outside the arid zone. They are vital for sustaining life in some of the driest parts of the world. For centuries, the annual floods of the Nile, Tigris, and Euphrates, for example, have brought fertile silts and water to the inhabitants of their lower valleys. Today, river discharges are increasingly controlled by human intervention, creating a need for international river-basin agreements. The filling of the Ataturk and other dams in Turkey has drastically reduced flows in the Euphrates, with potentially serious consequences for Syria and Iraq.

2. The word “drastically” in the passage is closest in meaning to

A. obviously

B. unfortunately

C. rapidly

D. severely

3. In paragraph 2, why does the author mention the Ataturk and other dams in Turkey?

A. To contrast the Euphrates River with other exogenous rivers

B. To illustrate the technological advances in dam building

C. To argue that dams should not be built on the Euphrates River

D. To support the idea that international river-basin agreements are needed

4. According to paragraph 2, which of the following is true of the Nile River?

A. The Nile's flow in its desert sections is at its lowest during the dry season

B. The Nile's sources are located in one of the most arid zones of the world

C. The Nile's annual floods bring fertile silts and water to its lower valley

D. The Nile's periodic flooding hinders the growth of some crops

Paragraph 5: Deserts contain large amounts of groundwater when compared to the amounts they hold in surface stores such as lakes and rivers. But only a small fraction of groundwater enters the hydrological cycle—feeding the flows of streams, maintaining lake levels, and being recharged (or refilled) through surface flows and rainwater. In recent years, groundwater has become an increasingly important source of freshwater for desert dwellers. The United Nations Environment Programme and the World Bank have funded attempts to survey the groundwater resources of arid lands and to develop appropriate extraction techniques. Such programs are much needed because in many arid lands there is only a vague idea of the extent of groundwater resources. It is known, however, that the distribution of groundwater is uneven, and that much of it lies at great depths.

5. The word “dwellers” in the passage is closest in meaning to

A. settlements

B. farmers

C. tribes

D. inhabitants

6. Paragraph 5 supports all of the following statements about the groundwater In deserts EXCEPT:

A. The groundwater is consistently found just below the surface

B. A small part of the groundwater helps maintain lake levels

C. Most of the groundwater is not recharged through surface water

D. The groundwater is increasingly used as a source of freshwater

Paragraph 6: Groundwater is stored in the pore spaces and joints of rocks and unconsolidated (unsolidified) sediments or in the openings widened through fractures and weathering. The water-saturated rock or sediment is known as an "aquifer". Because they are porous, sedimentary rocks, such as sandstones and conglomerates, are important potential sources of groundwater. Large quantities of water may also be stored in limestones when joints and cracks have been enlarged to form cavities. Most limestone and sandstone aquifers are deep and extensive but may contain groundwaters that are not being recharged. Most shallow aquifers in sand and gravel deposits produce lower yields, but they can be rapidly recharged. Some deep aquifers are known as "fossil waters. The term "fossil" describes water that has been present for several thousand years. These aquifers became saturated more than 10,000 years ago and are no longer being recharged.

7. The word “fractures” in the passage is closest in meaning to

A. streams

B. cracks

C. storms

D. earthquakes

8. According to paragraph 6, which of the following statements about aquifers in deserts is true?

A. Water from limestone and sandstone aquifers is generally better to drink than water from sand and gravel aquifers

B. Sand and gravel aquifers tend to contain less groundwater than limestone or sandstone aquifers

C. Groundwater in deep aquifers is more likely to be recharged than groundwater in shallow aquifers

D. Sedimentary rocks, because they are porous, are not capable of storing large amounts of groundwater

9. According to paragraph 6, the aquifers called fossil waters

A. contain fossils that are thousands of years old

B. took more than 10,000 years to become saturated with water

C. have not gained or lost any water for thousands of years

D. have been collecting water for the past 10,000 years