首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Geologists have been studying volcanoes for a long time. Though they have learned a great deal, they still have not discovered t
Geologists have been studying volcanoes for a long time. Though they have learned a great deal, they still have not discovered t
admin
2012-07-17
64
问题
Geologists have been studying volcanoes for a long time. Though they have learned a great deal, they still have not discovered the causes of volcanic action. They know that the inside of the earth is very hot, but they are not sure exactly what causes the great heat. Some geologists have thought that the heat is caused by the great pressure of the earth’s outer layers. Or the heat may be left from the time when the earth was formed. During the last sixty years scientists have learned about radium (镭), uranium (铀), thorium (钍), and other radioactive elements. These give out heat all the time as they change into other elements. Many scientists now believe that much of the heat inside the earth is produced by radioactive elements.
Whatever the cause of the heat may be, we do know that the earth gets hotter the farther down we dig. In deep mines and oil wells the temperature rises about 1 F. for each 50 feet. At this rate the temperature 40 miles below the earth’s surface would be over 4 000 F.. This is much hotter necessary to melt rock. However, the pressure of the rock above keeps most materials from melting at their usual melting points. Geologists believe that the rock deep in the earth may be plastic, or puttylike. In other words, the rock yields slowly to pressure but is not liquid. But if some change in the earth’s crust (地壳) releases the pressure, the rock melts. Then the hot, liquid rock can move up toward the surface.
When the melted rock works its way close to the earth’s crust, a volcano may be formed. The melted rock often contains steam and other gases under great pressure. If the rock above gives way, the pressure is released.
Then the sudden expansion of the gases causes explosions. These blow the melted rock into pieces of different sizes and shoot them high in the air. Here they cool and harden into volcanic ash and cinders (煤灰,余烬). Some of this material falls around the hole made in the earth’s surface. The melted rock may keep on rising and pour out as lava (熔岩,火山岩). In this way, volcanic ash, cinders, and lava build up the cone-shaped (圆锥形的) mountains that we call volcanoes.
From the information given in the passage, most minerals would melt fastest______.
选项
A、at 4 000 F. , at sea level
B、at 4 000 F. , 5 000 feet below sea level
C、at 4 000 F. , 5 000 feet above sea level
D、in the absence of oxygen
答案
B
解析
本题是一道具体细节题。问从文章所给的信息来看,大多数矿物质在什么条件下融化得更快。根据文章第二段,不管地热的原因是什么,我们确切知道往地下挖得越深,地球内越热。在深矿井和油井中,每向下挖50英尺,温度就升高1华氏度。以这种比率在地球表面下40英里的地方,温度将是4 000华氏度以上。这已足够熔化岩石了。因此,本题的正确答案应是B“在海平面以下5 000英尺的地方,温度是4 000华氏度时”。
转载请注明原文地址:https://kaotiyun.com/show/dEXO777K
0
在职攻硕英语联考
相关试题推荐
DuringMcDonald’searlyyearsFrenchfriesweremadefromscratcheveryday.RussetBurbankpotatoeswere【C1】______,cutintosh
DuringMcDonald’searlyyearsFrenchfriesweremadefromscratcheveryday.RussetBurbankpotatoeswere【C1】______,cutintosh
TheJapanesedesireformarriagehadbeenverystrong.Inthefifth""worldyouthattitudesurvey""【C1】______bytheManagementa
TheJapanesedesireformarriagehadbeenverystrong.Inthefifth""worldyouthattitudesurvey""【C1】______bytheManagementa
TheJapanesedesireformarriagehadbeenverystrong.Inthefifth""worldyouthattitudesurvey""【C1】______bytheManagementa
Cultureisactivityofthought,andreceptivenesstobeautyandhumanefeeling.【C1】______ofinformationhavenothingtodowith
Cultureisactivityofthought,andreceptivenesstobeautyandhumanefeeling.【C1】______ofinformationhavenothingtodowith
Cultureisactivityofthought,andreceptivenesstobeautyandhumanefeeling.【C1】______ofinformationhavenothingtodowith
Whethertheeyesare“thewindowsofthesoul”isdebatable;thattheyareintenselyimportantininterpersonalcommunicationis
随机试题
以下哪项是治疗肾癌的主要方法()
下列说法中正确的是()。
简述我国长期处于社会主义初级阶段的原因。
胃壁细胞质子泵抑制药是
茯苓的药用部分是
有爆炸危险的乙类生产部位,宜设置单层厂房靠外墙或多层厂房的()靠外墙处。
小王购买甲、乙两种特价商品。甲商品打八折后每件52元,乙商品打八五折后每件34元,小王购买这些商品总共比打折前节省了83元。问他购买这两种特价商品总共支出了多少元?
软件开发离不开系统环境资源的支持,其中必要的测试数据属于
为考生文件夹下的CAO文件夹建立名为CAO2的快捷方式,存放在考生文件夹下的HUE文件夹下。
Yourfatherisseriouslyiiiandyoushould______adoctoratonce.
最新回复
(
0
)