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
57
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.
Desert soils break up and crack because of____.
选项
A、the effects of wind and min
B、the lack of protection from the sun
C、the tropical location of deserts
D、the absence of rain
答案
B
解析
根据第二段第三旬“There are virtually no clouds or trees to protect the earth’s surfface andit can be burning hot.Under the sun,soils break up and crack…”可知,在沙漠地区没有云、没有树保护地面,地面很容易曝晒,因此裂开。B项说地面缺乏保护,符合句意。
转载请注明原文地址:https://kaotiyun.com/show/ZunO777K
0
考博英语
相关试题推荐
Conditionswere______treesvirtuallydisappearedfromtheinland,and40%ofAustraliawastransformedintoavastactivedune
Hewassoconvincedthatpeopleweredrivenby______motivesthathecouldnotbelievethatanyonecouldbeunselfish.
Schoolintegrationplansthatinvolvebusingbetweensuburbanandcentralcityareashavecontributed,accordingtoarecentstu
OnChristmasEveinAmericatheshoppingmallsaresaturatedwithshoppersinafranticcompetitionforlastminutegifts.
Youknowyoushoulddoit,otherpeopledoitallthetime.Maybeyou’vealreadydoneitbutitwasn’tverysatisfying,andyou
Scientists,likeotherpeople,arealwayspleasedtohavetheirownideas______.
有些人常常讥讽某个人好名,某个人爱出风头,其实只不过醋酸在暗暗作怪,恨自己没有露一手,一旦有机会可以露一手,也会照样露一手。一个人如果连荣誉心都没有,连好名声都不愿博取,则该人啥丧天害理的事,都可能干得出。人之异于禽兽者,在于人好名,禽兽不好名也。
Inasense,scientistsandengineersinthepasthavebeenfortunate,forwebecameaccustomedtobeingmeasuredbynatureitsel
Stablepoliticalconditionsandfreedom(from)foreigninvasionenableacountrytodevelopitsnaturalresourcespeacefullyand
Ifonedoesnotpickup(his)dry-cleaning(within)thirtydays,themanagementisnot(obligated)toreturnit(back).
随机试题
管理的核心是以人为本,这是因为()
某企业的采购部在收到生产需求部门直接提交的清购单后,由其职员E进行询价并确定供应商,再由其职员F负责编制和发出预先未经连续编号的订购单。采购的货物运达后,采购部根据订购单的要求验收货物,编制一式多联的未连续编号的验收单。验收单一联交采购部,登记采购明细账和
一患者患风湿顽痹,肢体麻木瘫痪,不慎又将上肢前臂摔伤,现肢体肿胀、疼痛。治疗宜首选的药物是
患者,男性,30岁。农民,既往体健。7月2日来诊,腹泻2天,为水样便,带少量黏液,量多,1天10余次,相继呕吐数次,无发热、无腹痛,腓肠肌痉挛。体检:体温36.8℃,神志清,皮肤弹性差,脉搏细速,血压70/30mm/Hg。化验检查:粪便镜检白细胞0~2个
()不得使用商业承兑汇票。
财政部门对各单位实施监督的主要事项包括()。
A公司向B汽车运输公司租人5输载重汽车,双方签订的合同规定,5辆载重汽车的总价值为240万元,租期3个月,月租金为0.4万元。则A、B两公司应缴印花税额合计为()。
下列几个句子的顺序已经被打乱,请重新排列,排列正确的一项是()。①大海里,闪烁着一片鱼鳞似的银波②一片片坐着、卧着、走着的人影,看得清清楚楚了③沙滩上,也突然明亮起来④它像一面光辉四射的银盘似的,从那平静的大海里涌了出来⑤月亮上
论述清末民初中国近代经济率先自东部兴起的原因。(南开大学2014年中国历史真题)
WhocomestotheChicagotradefaireachyear?
最新回复
(
0
)