托福阅读常考话题及练习题推荐五：地下水（3）

1托福阅读常考话题：地下水练习题

Paragraph 7: Water does not remain immobile in an aquifer but can seep out at springs or leak into other aquifers. The rate of movement may be very slow: in the Indus plain, the movement of saline (salty) groundwaters has still not reached equilibrium after 70 years of being tapped. The mineral content of groundwater normally increases with the depth, but even quite shallow aquifers can be highly saline.

10. The word “immobile” in the passage is closest in meaning to

A. enclosed

B. permanent

C. motionless

D. intact

11. The passage supports which of the following statements about water in the desert?

A. The most visible forms of water are not the most widespread forms of water in the desert.

B. Groundwater in the desert cannot become a source of drinking water but can be used for irrigation.

C. Most of the water in the desert is contained in shallow aquifers that are being rapidly recharged.

D. Desert areas that lack endogenous or exogenous rivers and streams cannot support life.

Paragraph 4: Regularly flowing rivers and streams that originate within arid lands are known as "endogenous." These are generally fed by groundwater springs, and many issue from limestone massifs, such as the Atlas Mountains in Morocco. Basaltic rocks also support springs, notably at the Jabal Al-Arab on the Jordan-Syria border. ■Endogenous rivers often do not reach the sea but drain into inland basins, where the water evaporates or is lost in the ground. ■Most desert streambeds are normally dry, but they occasionally receive large flows of water and sediment. ■

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.

12. Look at the four squares [■] that indicate where the following sentence could be added to the passage

These sudden floods provide important water supplies but can also be highly destructive.

Where would the sentence best fit?

13. Directions: Select from the seven sentences below, the two sentences that correctly characterize endogenous rivers and the three sentences that correctly characterize exogenous rivers. Drag each sentence you select into the appropriate column of the table. Two of the sentences will NOT be used. This question is worth 3 points.

Endogenous Rivers

Exogenous Rivers

Answer Choices

A. Their water generally comes from groundwater springs.

B. Their water is saltier than the water of most other rivers.

C. They include some of the world's largest rivers.

D. They originate outside the desert.

E. They often drain into inland basins and do not reach the sea.

F. They contain too much silt to be useful for irrigation.

G. Their water flow generally varies with the season of the year.