托福阅读常考话题及练习题推荐二：冰川（2）

► Paragraph 1：Glaciers are slowly moving masses of ice that have accumulated on land in areas where more snowfalls during a year than melts. Snow falls as hexagonal crystals, but once on the ground, snow is soon transformed into a compacted mass of smaller, rounded grains. As the air space around them is lessened by compaction and melting, the grains become denser. With further melting, refreezing, and increased weight from newer snowfall above, the snow reaches a granular recrystallized stage intermediate between flakes and ice known as firn. With additional time, pressure, and refrozen meltwater from above, the small firn granules become larger, interlocked crystals of blue glacial ice. When the ice is thick enough, usually over 30 meters, the weight of the snow and firn will cause the ice crystals toward the bottom to become plastic and to flow outward or downward from the area of snow accumulation.

1. The word “interlocked” in the passage is closest in meaning to

A. intermediate

B. linked

C. frozen

D. fully developed

2. According to paragraph 1, which of the following does NOT describe a stage in the development of firn?

A. Hexagonal crystals become larger and interlock to form a thick layer.

B. Snow crystals become compacted into grains.

C. Granules recrystallize after melting, refreezing, and further compaction.

D. Grains become denser owing to reduced air space around them.

► Paragraph 2： Glaciers are open systems, with snow as the system’s input and meltwater as the system's main output. The glacial system is governed by two basic climatic variables: precipitation and temperature. For a glacier to grow or maintain its mass, there must be sufficient snowfall to match or exceed the annual loss through melting, evaporation, and calving, which occurs when the glacier loses solid chunks as icebergs to the sea or to large lakes. If summer temperatures are high for too long, then all the snowfall from the previous winter will melt. Surplus snowfall is essential for a glacier to develop. A surplus allows snow to accumulate and for the pressure of snow accumulated over the years to transform buried snow into glacial ice with a depth great enough for the ice to flow. Glaciers are sometimes classified by temperature as faster-flowing temperate glaciers or as slower-flowing polar glaciers.

3. The word “match” in the passage is closest in meaning to

A. measure

B. enlarge

C. approximate

D. equal

4. The word “transform” in the passage is closest in meaning to

A. break

B. push

C. change

D. extend

5. According to paragraph 2, surplus snow affects a glacier in all the following ways EXCEPT:

A. It provides the pressure needed to cause glacial ice to flow.

B. It offsets losses of ice due to melting, evaporation, and calving.

C. It brings about the formation of firn in the snow it buries.

D. It results in temperate glaciers that are thicker than polar glaciers.

6. Paragraph 2 implies that which of the following conditions produces the fastest moving glaciers?

A. A climate characteristic of the polar regions

B. A thick layer of ice in a temperate climate

C. Long, warm summers

D. Snow, firn, and ice that have been buried for several years

► Paragraph 3： Glaciers are part of Earth’s hydrologic cycle and are second only to the oceans in the total amount of water contained. About 2 percent of Earth’s water is currently frozen as ice. Two percent may be a deceiving figure, however, since over 80 percent of the world’s freshwater is locked up as ice in glaciers, with the majority of it in Antarctica. The total amount of ice is even more awesome if we estimate the water released upon the hypothetical melting of the world’s glaciers. Sea level would rise about 60 meters. This would change the geography of the planet considerably. In contrast, should another ice age occur, sea level would drop drastically. During the last ice age, sea level dropped about 120 meters.

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

A. approximate

B. exaggerated

C. unusual

D. misleading

8. Why does the author consider the hypothetical melting of the world's glaciers?

A. To contrast the effects of this event with the opposite effects of a new ice age

B. To emphasize how much water is frozen in glaciers

C. To illustrate the disastrous effects of a warming trend

D. To support the claim that glaciers are part of Earth's hydrologic cycle

9. The discussion in paragraph 3 answers all the following questions EXCEPT:

A. Where is most of Earth's freshwater?

B. What effect would a new ice age have on sea levels?

C. What is the total amount of water in Earth's oceans?

D. How much of Earth's water is in ice?