Volcanoes are the landforms created whenmoltenrock, ormagma, escapes from vents in the Earth’s surface and then solidifies around these vents. In anygivenyear,roughly50 of Earth’s active volcanoeserupt— usually with some warning. Before they blow, they typically shake,swell, warm up, and belch avarietyof gases. Scientists from theVolcanoDisasterAssistanceProgram VDAP—part of the U.S. GeologicalSurveyand based at the U.S. GeologicalSurvey’s CascadesVolcanoObservatory in Vancouver, Washington—are always on call, ready when summoned torushat a moment’s notice to an awakeningvolcanoanywhere in the world; armed with the latest in lasers, seismometers, and other monitoring devices, they canassessthevolcano’spotentialfor violence andpredictwhen it might ignite.

Geologists have enjoyedfairsuccess in predictingindividualeruptive episodes when theyconcentrateon aspecificvolcanoafter an eruptivephasehas begun. These monitoring efforts involve carefully measuring changes in avolcano’s surfacetemperature, watching for the slightestexpansionin itsslope, and keepingtrackof regional earthquakeactivity. Alaboratoryat the University of Washington in Seattle is staffed 24 hours a day tomonitorthe rumblings ofMountSt. Helens. Evenwith the advances brought by today’s technology, however, the art ofvolcanoprediction has not been fully mastered. The U.S. GeologicalSurveymissed the call onMountSt. Helens’ 1980blastdespite the fact that the mountain was being watched closely by a large team of scientists armed with the latest in prediction technology. It did successfullypredicttheeruptionofMountPinatubo in the Philippines, evacuatingvirtuallyeveryonewithin25 kilometers (15 miles) before thevolcano’s powerfulblaston May 17,1991.

Before avolcanoerupts, hotmagmarises toward the surface, so anylocalmanifestationof increasing heat maysignalanimpendingevent. Ongoingsurveys canidentifynew surface hot springs and take thetemperatureof the water and steam in existing ones. If the escaping steam isn’t much hotter than the boiling point of water， then surface water is probably seeping into the mountain and being heated bycontactwith hotsubsurfacerocks, and all is well for the time being. If the steam is superheated, with temperatures as high as 500° C (900° F), then it probably derives fromshallowwater-richmagma, a sign that aneruptionmay be brewing. Asmagmarises, thevolcaniccone itself begins to heat up. Theoveralltemperatureof avolcaniccone can be monitored from an orbitingsatelliteequipped withinfraredheat sensors todetectthe slightest change in surfacetemperature. This high-altitude technology serves as asimultaneousearly-warning system for most of Earth’s 600 or so active volcanoes. Impendingeruptions may also be predicted by increased gas emissions from rising magmas. For thisreason, volcanologists continuouslymonitorsulfurdioxideandcarbondioxideemissions from potentially active volcanoes.

Active volcanoesexpandinvolumeas theyacquirenew supplies ofmagmafrom below. As a result, an increase in the steepness or bulging of avolcano’sslopemaysignalanimpendingeruption. Todetecttheinflationof avolcaniccone, atiltmeter, adevicelike a carpenter’slevel, is used. Asmagmarises, it pushes aside fractured rock, enlarging the fractures as it moves. Because this type of fracturing causes earthquakes, eruptions are often preceded by adistinctivepatternof earthquakeactivitycalledharmonictremors, acontinuousrhythmicrumbling. Sensitiveequipment that monitors the location where these tremorsoccurcanmeasurethe increased height of risingmagma. Therateat which themagmarises provides anestimateof when aneruptionmayoccur. Indeed, it served as theprincipalmeans by which scientists accurately predicted recent eruptions ofMountSt. Helens.

Efforts topredicteruptions are thwarted, however, when we are unaware of a site’svolcanicpotential. Occasionally, a newvolcanoappears suddenly and rather unexpectedly, as was the case in 1943, when thevolcanoParicutin developedliterallyovernightin the Mexicanstateof Michoacan, 320 kilometers (200 miles) west of Mexico City. The surrounding area was known to bevolcanicbecause of its geologiczone, but it was not possible topredictthat thevolcanowouldappearat thisparticularsite. Ourabilitytopredictvolcaniceruptions continues toimprovebut is not yet asaccurateas we need it to be.

Questions:
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: Scientists based at the U.S. Geological Survey’s Cascade Volcanic Observatory in Vancouver, Washington are always being asked to rush somewhere to predict when a volcano is likely to awake and, if it erupts, what damage it could do.

tag: B
text: Armed with the latest technology, U.S. Geological Survey scientists from the Volcano Disaster Assistance Program are always available to go anywhere in the world to assess whether, and when, an awakening volcano will erupt.

tag: C
text: In order to learn how to predict when an awakening volcano will erupt, scientists from the Volcano Disaster Assistance Program take the latest lasers, seismometers, and other monitoring devices wherever there is an awakening volcano.

tag: D
text: U.S. Geological Survey scientists from the Cascade Volcanic Observatory in Vancouver, Washington have the latest lasers, seismometers, and other monitoring devices which they use in assessing volcanoes worldwide to predict which of them will erupt violently.
answer_key: B
explanation: 分析原句的句子结构，该句的主干信息为 Scientists from the Volcano Disaster Assistance Program (VDAP) are always on call, ready when summoned to rush at a moment’s notice to an awakening volcano anywhere in the world；they can assess the volcano’s potential for violence and predict when it might ignite，大致意思为：来自于 VDAP 的科学家们随时待命，随时准备在接到通知的瞬间冲向世界上任何一个正在苏醒的火山;他们配备了最新的激光、地震仪和其他监测设备，可以评估火山是否会爆发以及何时爆发。原句中“—part of the U.S. Geological Survey and based at the U.S. Geological Survey’s Cascades Volcano Observatory in Vancouver, Washington—”为插入语，解释说明 VDAP。A 中的 if it erupts, what damage it could do（预测爆发后可能造成的破坏）这一点原句并未提到，不符合；B 正确，选项大意意思为：配备最新的技术装备，来自 VDAP 的科学家们随时可以前往世界任何地方，评估一个正在苏醒的火山是否会爆发，以及何时会爆发。改选项的意思与原句意思相符；C 的大致意思是：为了了解如何预测一个觉醒的火山何时会爆发，科学家们在有觉醒的火山的地方使用最新的激光器、地震仪和其他监测设备。改选项中的目的原句并未提到，而且原句的主干意思“科学家们随时待命，随时准备在接到通知的瞬间冲向世界上任何一个正在苏醒的火山”选项里也未体现，不能选；D 的大致意思为：科学家拥有最新监测设备，并利用这些设备来评估世界各地的火山，预测哪座火山会猛烈爆发。首先该选项未提及原句的主干信息，其次，选项中提到的“评估世界各地的火山，预测哪座火山会猛烈爆发”与原句意思不符合。故而该题选 B。

question_stem: The fact that “The U.S. Geological Survey missed the call on Mount St. Helens’1980 Blast”supports which of the following points?
choices: tag: A
text: Monitoring efforts need to be combined with appropriate evacuation strategies.

tag: B
text: Technology needs to be specifically designed to predict volcanoes.

tag: C
text: It is easier to predict volcanoes in the Philippines than it is in Seattle.

tag: D
text: Even with the help of technology, it is still difficult to predict when volcanoes will erupt.
answer_key: D
explanation: 题干问这个事实支持哪一个观点，也就是说该信息在文段中可能是一个实例，上下文中可能出现它所支持的观点；定位信息到第二段的第5句话，该句的大致意思是美国地质勘探局错过了1980年圣海伦斯火山的爆炸，尽管这座山当时正被最新预测技术监测着。考虑上下文，发现前一句话意思与该实例很类似——Even with the advances brought by today’s technology, however, the art of volcano prediction has not been fully mastered. 大致意思为：然而，即使有了当今先进技术，火山预测的技术仍未被完全掌握。所以该句子就是题干提到的实例所支持的观点。对照选项，符合的即为 D：即使有技术的帮助，仍然很难预测火山何时爆发。

question_stem: Why does the author mention the successful prediction of “the eruption of MountPinatubo”?
choices: tag: A
text: To support the claim that the art of volcano prediction will never be fully mastered

tag: B
text: To provide a contrast with the failure to predict the Mount St. Helens eruption

tag: C
text: To show that volcano prediction had been perfected by 1991

tag: D
text: To show that successful volcano prediction depends on concentrating on the volcano after an eruptive phase has begun
answer_key: B
explanation: 首先定位题干信息到第二段最后一句话，大致意思为：它确实成功地预测了菲律宾皮纳图博火山的爆发，并1991年5月17日火山爆发前疏散了25公里(15英里)内的几乎所有人。考虑前文信息，寻找该句表达的意思与前文的关系。前句也是个实例，解释即使有先进技术也无法完全预测火山爆发，与定位信息句的实例刚好相反；因此是作为一个比较对象出现，跟前文的预测失败做对比；故而答案选 B，目的是为了与未能预测圣海伦斯火山爆发的事件形成对比。

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

tag: B
text: measurement

tag: C
text: possibility

tag: D
text: effects
answer_key: A
explanation: manifestation：表现、显示、表征；意思符合的即为 A indication：指示、迹象，不符合；B  measurement 测量，不符合；C possibility 可能性，不符合；D effects 影响、效果，不符合。

question_stem: According to paragraph 3, why is superheated steam in a surface hot spring a sign that an eruption may be developing?
choices: tag: A
text: Superheated steam shows how hot the subsurface rocks have become.

tag: B
text: Superheated steam occurs only after the volcanic cone has become extremely hot.

tag: C
text: Superheated steam indicates an increase in gas emissions.

tag: D
text: Superheated steam is likely to come from water-rich magma near the surface.
answer_key: D
explanation: 题干审仔细，在问：为什么表面温泉中的过热的蒸汽可以表明火山喷发可能正在发展？根据题干关键词 superheated steam 定位到本段第4句话 If the steam is superheated, with temperatures as high as 500° C (900° F), then it probably derives from shallow water-rich magma, a sign that an eruption may be brewing. 大致意思为：如果蒸汽超级热，温度高达500摄氏度(900华氏度)，那么它可能来自于浅处的富含水的岩浆，这是可能火山即将爆发的迹象。所以答案已经在本句给出，即这个过热的蒸汽可能来自于浅处的富含水的岩浆，所以答案选 D。

question_stem: The word “principal”in the passage is closest in meaning to
choices: tag: A
text: most important

tag: B
text: most common

tag: C
text: most accurate

tag: D
text: Empirical
answer_key: A
explanation: principal：在文本中是“主要的，首要的”意思，选项符合的即为 A 最重要的；B 最普遍的；C 最精准的；D 经验主义的。

question_stem: In paragraph 4, the mention of the accurate prediction of recent eruptions of Mount St. Helens serves to
choices: tag: A
text: emphasize the decisive role of new technology in accurately predicting when a volcano is likely to erupt

tag: B
text: illustrate the effectiveness of tilt meters in predicting volcanic eruptions

tag: C
text: provide an example of how monitoring certain distinctive patterns of earthquake activity can provide a reliable indication of where an eruption will occur

tag: D
text: support the claim that the rate at which magma rises is a good indicator of when an eruption will occur
answer_key: D
explanation: 该题类似于功能目的题，即提到圣海伦斯火山最近喷发的准确预测是为了…？先定位题干信息到本段的最后一句话 Indeed, it served as the principal means by which scientists accurately predicted recent eruptions of Mount St. Helens.大致意思为：的确，它是科学家们准确预测最近圣海伦斯火山爆发的主要手段。这句话中体现出了预测最近圣海伦斯火山爆发的主要方法的准确性；往前结合信息，发现前一句提到了岩浆上升的速度可用来估算火山爆发的时间，所以提到 the accurate prediction of recent eruptions of Mount St. Helens 目的是为了用证明前句所表达的论点：The rate at which the magma rises provides an estimate of when an eruption may occur；所以答案选 D。

question_stem: According to paragraph 5, each of the following features of the appearance of the volcano Paricutin was a surprise to scientists EXCEPT
choices: tag: A
text: the particular site at which it appeared

tag: B
text: the geologic zone in which it appeared

tag: C
text: the rate at which it developed

tag: D
text: the timing of its appearance
answer_key: B
explanation: 题干问 Paricutin 火山的下列哪一个特征没有令科学家们感到惊讶。四个选项信息分别为：A 出现的地点，对应到倒数第二句中的 but it was not possible to predict that the volcano would appear at this particular site，符合惊讶，排除；B 出现的地质带，也是对应到倒数第二句中 The surrounding area was known to be volcanic because of its geologic zone，也就是关于地质带这点是已经了解的，所以并不惊讶，选 B；C 发展的速度，对应到第二句中的 a new volcano appears suddenly and rather unexpectedly, as was the case in 1943, when the volcano Paricutin developed literally overnight in the Mexican state of Michoacan，出乎意料在一夜之间就发展起来了，所以关于速度这点也令人惊讶，排除；D 出现的时间，也是对应到第二句 a new volcano appears suddenly and rather unexpectedly，突然出现，令人惊讶，排除。