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 compactedmassof smaller, rounded grains. As theairspacearound them is lessened by compaction andmelting, the grains become denser. With furthermelting, refreezing, and increased weight from newer snowfall above, the snow reaches agranularrecrystallizedstageintermediatebetween flakes and ice known as firn. Withadditionaltime,pressure, and refrozen meltwater from above, the small firn granules become larger,interlockedcrystals of blueglacialice. 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 becomeplasticand to flow outward ordownwardfrom the area of snowaccumulation.

Glaciers are open systems, with snow as the system’s input and meltwater as the system's mainoutput. Theglacialsystem is governed by twobasicclimaticvariables:precipitationandtemperature. For aglacierto grow ormaintainitsmass, there must besufficientsnowfall tomatchorexceedtheannuallossthroughmelting,evaporation, and calving, which occurs when theglacierlosessolidchunks as icebergs to the sea or to large lakes. If summer temperatures are high for too long, then all the snowfall from thepreviouswinter willmelt. Surplussnowfall isessentialfor aglacierto develop. Asurplusallows snow toaccumulateand for thepressureof snow accumulated over the years totransformburied snow intoglacialice with a depth great enough for the ice to flow. Glaciers are sometimes classified bytemperatureas faster-flowingtemperateglaciers or as slower-flowingpolarglaciers.

Glaciers are part of Earth’shydrologiccycleand aresecondonly to the oceans in the totalamountof water contained. About 2 percent of Earth’s water is currently frozen as ice. Two percent may be a deceivingfigure, however, since over 80 percent of the world’s freshwater is locked up as ice in glaciers, with themajorityof it inAntarctica. The totalamountof ice isevenmoreawesomeif weestimatethe water released upon thehypotheticalmeltingof the world’s glaciers. Sealevelwould rise about 60 meters. This would change the geography of theplanetconsiderably. Incontrast, should another ice ageoccur, sealevelwoulddropdrastically. During the last ice age, sealeveldropped about 120 meters.

When snowfalls on high mountains or inpolarregions, it may become part of theglacialsystem. Unlike rain, which returns rapidly to the sea oratmosphere, the snow that becomes part of aglacieris involved in a much more slowly cycling system. Here water may be stored in ice form for hundreds orevenhundreds of thousands of years before being released again into theliquidwater system as meltwater. In themeantime, however, this ice is notstatic. Glaciers move slowlyacrossthe land withtremendousenergy, carving intoeventhe hardest rock formations andtherebyreshaping thelandscapeas theyengulf, push,drag, and finallydepositrockdebrisin places far from itsoriginallocation. As a result, glaciers create a greatvarietyof landforms thatremainlong after the surface is released from its icy covering.

Throughoutmost of Earth’shistory, 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 inAntarctica, 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 wasperiodicallycovered by ice thousands of meters thick. In the much moredistantpast, other ice ages have occurred.

Questions:
question_stem: The word “interlocked” in the passage is closest in meaning to
choices: tag: A
text: intermediate

tag: B
text: linked

tag: C
text: frozen

tag: D
text: fully developed
answer_key: B
explanation: interlock 连锁，连接，所以 B 的 link 正确。从单词本身看，inter 表示在……之间，lock 表示锁，所以这个词应该是锁在什么什么中间的意思，所以 link 靠谱，frozen 只表示锁，没有之间，所以不对；而 intermediate 只表示在……之间，没有固定的意思，所以不对；fully develop 完全不对。

question_stem: According to paragraph 1, which of the following does NOT describe a stage in the development of firn?
choices: tag: A
text: Hexagonal crystals become larger and interlock to form a thick layer.

tag: B
text: Snow crystals become compacted into grains.

tag: C
text: Granules recrystallize after melting, refreezing, and further compaction.

tag: D
text: Grains become denser owing to reduced air space around them.
answer_key: A
explanation: A 的 hexagonal crystal 做关键词定位至第二句，但原文没说形成 thick layer，A 错，选；B 的 compact 和 grain 做关键词同样定位至第二句，正确，不选；C 的 granules 做关键词定位至倒数第三句，正确，不选；D 的 air space 做关键词定位至第三句，正确，不选。

question_stem: The word “match” in the passage is closest in meaning to
choices: tag: A
text: measure

tag: B
text: enlarge

tag: C
text: approximate

tag: D
text: equal
answer_key: D
explanation: match 匹配，所以 equal 是答案。原句说冰川如果想保持其体积不变或者增大，必须有足够的降雪量来怎么样或者超过融化已经其他过程造成的损失，肯定是先说弥补上，再说超过，所以 equal 相等，相当正确。measure 完全不对；approximate 接近不行，因为只是接近的话没法保持冰川体积不变；enlarge 和 exceed 意思一样，不选。

question_stem: The word “transform” in the passage is closest in meaning to
choices: tag: A
text: break

tag: B
text: push

tag: C
text: change

tag: D
text: extend
answer_key: C
explanation: transform 形变，变形，所以 C 的 change 正确。从单词本身看，trans 表示转移，转换，form 形式，所以整个单词应该是变形之意。原句说降雪量超过融化的量剩余的那些雪经过若干年后能形成必要把雪怎么成冰川的压力，当然是变成冰川，所以 change 正确。

question_stem: According to paragraph 2, surplus snow affects a glacier in all the following ways EXCEPT:
choices: tag: A
text: It provides the pressure needed to cause glacial ice to flow.

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

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

tag: D
text: It results in temperate glaciers that are thicker than polar glaciers.
answer_key: D
explanation: EXCEPT 题，排除法。A 的 pressure 做关键词定位至倒数第二句，正确，不选；B 的三个动名词和做关键词定位至第二句，正确，不选；C 的 firn 做关键词定位至前一段的倒数第三句，正确，不选；D 的两种 glaciers 做关键词定位至最后一句，两者是并列关系，没有谁比谁怎么样，所以 D 错，选。

question_stem: Paragraph 2 implies that which of the following conditions produces the fastest moving glaciers?
choices: tag: A
text: A climate characteristic of the polar regions

tag: B
text: A thick layer of ice in a temperate climate

tag: C
text: Long, warm summers

tag: D
text: Snow, firn, and ice that have been buried for several years
answer_key: B
explanation: 以 fast moving glaciers 做关键词定位至最后一句，说冰川可以按温度分为快速移动的 temperate 和慢速移动的 polar，所以要快速移动就必须得是 temperate，所以 A 和 C 说反，D 压根儿没提气候的事儿，所以正确答案是 B。

question_stem: The word “deceiving” in the passage is closest in meaning to
choices: tag: A
text: approximate

tag: B
text: exaggerated

tag: C
text: unusual

tag: D
text: misleading
answer_key: D
explanation: deceive 欺骗，所以 deceiving 欺骗性的，所以 D 的 misleading 正确。原句说2%是个什么样的数字，因为全球约有80%的淡水是以冰川的形式存在的，大部分都在南极洲，从作者的 however 猜出作者对于这个数字的态度是不太信任的，所以答案是 D，作者的意思是2%少了，所以 exaggerated 夸张不对；approximate 无贬义；unusual 完全不靠谱。

question_stem: Why does the author consider "the hypothetical melting of the world's glaciers"?
choices: tag: A
text: To contrast the effects of this event with the opposite effects of a new ice age

tag: B
text: To emphasize how much water is frozen in glaciers

tag: C
text: To illustrate the disastrous effects of a warming trend

tag: D
text: To support the claim that glaciers are part of Earth's hydrologic cycle
answer_key: B
explanation: 说如果考虑到全球冰川融化释放出的水量，这个量是相当惊人的，如果不知道选什么，往前看，但前文仍然是一个例子，所以也不对，中心句说冰川是地球上的仅次于大洋的第二大水源，所以这些无外乎都是在说冰川水很多，所以答案是 B。

question_stem: The discussion in paragraph 3 answers all the following questions EXCEPT:
choices: tag: A
text: Where is most of Earth's freshwater?

tag: B
text: What effect would a new ice age have on sea levels?

tag: C
text: What is the total amount of water in Earth's oceans?

tag: D
text: How much of Earth's water is in ice?
answer_key: C
explanation: A 的 freshwater 做关键词定位至第三句，原文说80%，肯定是最大来源了，所以 A 对，不选；B 的 ice age 和 sea level 做关键词定位至最后两句，正确，不选；C 的 total amount 在原文没有对应点，错，选；D 的 ice 和 Earth’s water 做关键词定位至第二句，正确，不选。

question_stem: The word “static” in the passage is closest in meaning to
choices: tag: A
text: unchanging

tag: B
text: usable

tag: C
text: thick

tag: D
text: harmless
answer_key: A
explanation: A static: 静止的。A 是不变的；B 是可使用的；C 是厚的；D 是无害的。所以 A 的 unchanging 正确。

question_stem: Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.
choices: tag: A
text: As a glacier moves, it leaves behind rock formations that have been engulfed, pushed, and dragged by the glacier.

tag: B
text: Glaciers reshape the landscape by carving into rock and transporting the resulting debris to distant locations.

tag: C
text: Glaciers carve the hardest rock formations with great energy and slowly reshape them into debris.

tag: D
text: The tremendous energy of slowly moving glaciers transports and finally deposits rock debris into large rock formations.
answer_key: B
explanation: B 原句的结构是冰川穿过陆地，carving blabla thereby reshaping blabla，所以 B 正确。A 遗漏了原文 reshaping 这个关键信息，错；C 错，原文 reshape 的是 landscape，答案 reshape 的是石头；D 完全改变了原文结构，错。

question_stem: According to paragraph 5, in what way is the present time unusual in the history of Earth?
choices: tag: A
text: There are glaciers.

tag: B
text: More land is covered by glaciers than at anytime in the past.

tag: C
text: There is no ice age.

tag: D
text: No glaciers are found in Australia.
answer_key: A
explanation: 以 present time 做关键词定位至第一句，说地球历史上是不存在冰川的，而现在有10%的地球表面被冰川覆盖，这就是现在 unusual 的原因，所以答案是 A，有冰川。B 的 anytime 太多绝对，原文只是说大部分的时候没有冰川；C 和原文说反；D 答非所问。