托福阅读常考话题及练习题推荐六：地下水（3）

1托福阅读常考话题：地下水练习题

Paragraph 6: A given lake's residence time is by no means a fixed quantity. It depends on the rate at which water enters the lake, and that depends on the rainfall and the evaporation rate. Climatic change (the result of global warming?) is dramatically affecting the residence times of some lakes in northwestern Ontario. Canada. In the period 1970 to 1986, rainfall in the area decreased from 1,000 millimeters to 650 millimeters per annum, while above-average temperatures speeded up the evapotranspiration rate (the rate at which water is lost to the atmosphere through evaporation and the processes of plant life). The result has been that the residence time of one of the lakes increased from 5 to 18 years during the study period. The slowing down of water renewal leads to a chain of further consequences: it causes dissolved chemicals to become increasingly concentrated, and this, in turn, has a marked effect on all living things in the lake.

10. The word further in the passage is closest in meaning to

A. expected

B. additional

C. serious

D. unfortunate

11. According to paragraph 6, which of the following explains the increase in residence time of some lakes of northwestern Ontario?

A. The amount of water flowing into the lakes has increased.

B. The rate of evaporation has decreased more sharply than the amount of rainfall.

C. The renewal of the lakes' water has slowed due to changes in climate.

D. Plants have required less water from the lakes

12.According to paragraph 6, residence time is affected by all of the following EXCEPT

A. amount of rainfall

B. rate of evaporation

C. temperature of surrounding air

D. concentration of chemicals in lake water

Paragraph 3: Once all this information has been gathered, it becomes possible to judge whether a lake’s flow is mainly due to its surface inputs and outputs or to its underground inputs and outputs. [■] If the former are greater, the lake is a surface-water-dominated lake; if the latter, it is a seepage-dominated lake. [■] Occasionally, common sense tells you which of these two possibilities applies. [■] For example, a pond in hilly country that maintains a steady water level all through a dry summer in spite of having no streams flowing into it must obviously be seepage dominated. Conversely, a pond with a stream flowing in one end and out the other, which dries up when the stream dries up, is clearly surface water dominated. [■]

13.Look at the four squares III that indicate where the following sentence could be added to the passage.

Of course, a lake may be neither surface-water-nor seepage-dominated if, for example, its inputs are predominantly surface and its outputs are predominantly seepage.

Where would the sentence best fit? Click on a square to add the sentence to the passage.

14.Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage.

This question is worth 2 points.

Water enters, remains, and eventually leaves a lake in a variety of ways.

Answer Choices

A. By measuring the water quantities at each of a lake's inputs and outputs, it can be determined whether water enters the lake mainly from surface or groundwater sources.

B. Changes in lake level and volume are caused principally by the amount of evaporation of water into the atmosphere.

C. It is sometimes possible to decide whether a lake is surface water dominated or seepage dominated by simple observation at different seasons.

D. The average period of time that molecules of water spend in a lake—the residence time—varies from lake to lake and overtime within a particular lake.

E. The residence times of surface-water-dominated lakes are usually longer than those of seepage-dominated lakes.

F. The residence time of a lake frequently depends on the kinds of organisms to be found in the lake.