Paragraph2: 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.
6. Paragraph 2 implies that which of the following conditions produces the fastest moving glaciers?
○A climate characteristic of the polar regions
○A thick layer of ice in a temperate climate
○Snow, firn, and ice that have been buried for several years
注意题目问文章“暗示”了下列哪种情形有“fastest”的moving glacier。说明是一道推断题吧。文中在说明温度因素的时候说温带的比极地得快，但没说温带的最快，对吧？暗含的意思是温度越高就会faster。那显然选C啊。C选项的温度最高。有人会说热带没冰川，谁说C一定指的是热带了？温带没有漫长的夏季？
Parargraph5: Throughout most of Earth’s history, glaciers did not exist, but at the present time about 10 percent of Earth’s land surface is covered by glaciers. Present-day glaciers are found in Antarctica, in Greenland, and at high elevations on all the continents except Australia. In the recent past, from about 2.4 million to about 10,000 years ago, nearly a third of Earth’s land area was periodically covered by ice thousands of meters thick. In the much more distant past, other ice ages have occurred.
12. According to paragraph 5, in what way is the present time unusual in the history of Earth?
○There are glaciers.
○More land is covered by glaciers than at anytime in the past.
○There is no ice age.
○No glaciers are found in Australia.
这题争议挺多的，问最后不是说还有各种时期被冰覆盖吗？再说了，如果真的A成立。说没有glacier。那么当今陆地被glacier覆盖的多不是“联欢晚会突出联欢”这样的真理吗？因为过去就没glacier，所以现在glacier就是比过去覆盖的多。
14. Glaciers are part of Earth's hydrologic cycle.
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●
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○Glaciers, which at present contain 80 percent of Earth's freshwater, form when accumulated snow is compressed and recrystallized into ice over a period of years.
○When there are glaciers on Earth, water is cycled through the glacier system, but the cycle period may be hundreds of thousands of years during periods of ice ages.
○The glacial system is governed by precipitation and temperature in such a way that glaciers cannot form in temperate latitudes.
○When glacial ice reaches a depth of 30 meters, the weight of the ice causes ice crystals at the bottom to flow, and the resulting movement of the glacier carves the landscape.
○If global warming melted the world's glaciers, sea level would rise about 60 meters worldwide.
○Glaciers have had little effect on Earth's surface because only 2 percent of Earth's water is currently contained in glaciers, and there are fewer glaciers now than at most times in the past.
人家问的是“hydrologic cycle”，4选项虽然对但它和水循环有半毛钱关系啊。有密切关系的显然是5选项吧。大家做的时候看没看题目啊？生选的？ | 
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发表于 2011-9-6 09:08:15
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