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
A scorching sun, an endless sea of sand and a waterless, forbiddingly lonely land—that is the image most people have of deserts.
A scorching sun, an endless sea of sand and a waterless, forbiddingly lonely land—that is the image most people have of deserts.
admin
2012-06-18
40
问题
A scorching sun, an endless sea of sand and a waterless, forbiddingly lonely land—that is the image most people have of deserts. But how true is this picture? Deserts are dry lands where rainfall is low. This is not to say rain never falls in deserts: it may fall once or twice a year in a fierce torrent that fades almost as soon as it has begun, or which evaporates in the hot air long before it has got anywhere near the earth. It may fall in a sudden sweeping flood that carries everything in its path. Rains may only come once in five or six years or not fall for a decade or more. The Mojave desert in the United States remained dry for twenty-five years.
Without water no living thing can survive, and one feature of the true desert landscape is the absence of vegetation. With little rain and hardly any vegetation the land suffers under the sun. There are virtually no clouds or trees to protect the earth’s surface and it can be burning hot. Under the sun, soils break up and crack. Wind and torrential rain sweep away and erode the surface further. Eight million square kilo-meters of the world’s land surface is desert. Throughout history deserts have been expanding and re-treating again. Cave paintings show that parts of the Sahara Desert were green and fertile about 10,000 years ago, and even animals like elephants and giraffes roamed the land. Fossil and dunes found in fer-tile and damp parts of the world show that these areas were once deserts. But now the creation of new desert areas is happening on a colossal scale. Twenty million square kilometers, an area twice the size of Canada, is at a high to very high risk of becoming desert. With a further 1.25 million square kilometers under moderate risk, an area covering 30% of the earth’s land surface is desert, becoming desert, or in danger of becoming desert. The rate of growth of deserts is alarming. The world’s dry lands which are under threat include some of the most important stock-rearing and wheat-growing areas and are the homes of 600~700 million people. These regions are becoming deserts at the rate of more than 58,000 square kilometers a year or 44 hectares a minute. In North Africa at least 100,000 hectares of cropland are lost each year. At this rate there is a high risk that we will be confined to living on only 50% of this planet’s land surface within one more century unless we are able to do something about it.
What do we learn about deserts from this text?
选项
A、Deserts can change into green and fertile areas.
B、Certain areas have always been desert.
C、Deserts were once the home of elephants and giraffes.
D、Deserts have been growing since the beginning of the world.
答案
A
解析
答案在文章第二段第五行“Throughout history deserts have been expanding and retreating again.”,从这段可知,一些肥沃的地方以前曾经是沙漠。而现在的沙漠以前也曾经是沃土和绿洲,所以A项正确。
转载请注明原文地址:https://kaotiyun.com/show/4unO777K
0
考博英语
相关试题推荐
When(imaginable)scientists(first)suggestedthepossibilitythatoneperson(couldspeak)directlytoanother(over)alongd
Governmentswillbeinvitedto______theassessment’stechnicalleadauthors.
Therangeinfrequenciesofmusicalsoundsisapproximately20-20,000cyclespersecond(cy/sec),Somepeoplecanhearhigherf
Hewassoconvincedthatpeopleweredrivenby______motivesthathecouldnotbelievethatanyonecouldbeunselfish.
Theboyhadaviolentpaininhisstomachaftereatingtoomuchice-cream.
Fromthehealthpointofviewwearelivinginamarvelousage.Weareimmunizedfrombirthagainstmanyofthemostdangerousd
Theoldmusiciandecidedtomovetohercountryhome______heradvancedageandpoorhealth.
在现今竞争激烈的社会中,每个人都免不了承受很多压力。这些心理的和社会的压力诱因包括亲密关系的破裂、家庭成员或朋友的去世、经济困境、角色冲突、超负荷工作、失业、歧视、健康不佳、照料年迈的父母、意外伤害和对人身安全的故意攻击。长期的压力会引起身体、情感和行为问
ThetraditionalAmericanThanksgivingDaycelebration【1】to1621.【2】thatyearaspecialleastwaspreparedinPlymouth,Massachus
We’veallheardaboutwhalewatchingfromboatsorshore,andafewcompaniesarenowofferingthepossibilityofactuallyswimmi
随机试题
诊断慢性肾盂肾炎时,下列哪项不正确
有关热原检查法叙述不正确的是
A.最易出现癫痫发作B.出现内分泌功能障碍C.典型症状是遗忘综合征D.躁狂发作E.典型症状是幻视第三脑室附近脑瘤
受到高热、磨擦、冲击后能产生剧烈反应而发生大量气体和热量,引起爆炸的化学药品是具有强烈腐蚀性,甚至引起燃烧、爆炸和杀伤性药品是
两个卡诺热机的循环曲线如图2—1—4所示,一个工作在温度为T1与T4的两个热源之间,另一个工作在温度为T2与T3的两个热源之间,已知这两个循环曲线所包围的面积相等。由此可知,下列关于两个热机效率和吸热情况的叙述正确的是()。
下列关于建设项目环境影响评价的分类管理的说法,错误的是()。
顾客在购买一件产品时所感受到的产品效用与购买成本的比值,也就是他的所得与所付之比,即为()。
设方程组其中ai≠aj(i≠j),则下列说法中正确的().
Readthearticlebelowaboutthebusiness’socialresponsibilityandthequestions.Foreachquestion(13-18),markoneletter(
Therearemoredrugsdispensedforpainthanforanyotherdiseaseonthisplanet.Drugcompaniesenjoyearninghugeprofitsf
最新回复
(
0
)