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
The wide variety of climates in North America has helped spawn a complex pattern of soil regions. In general, the real
The wide variety of climates in North America has helped spawn a complex pattern of soil regions. In general, the real
admin
2005-01-30
80
问题
The wide variety of climates in North America has helped spawn a complex pattern of
soil regions. In general, the realm’s soils also reflect the broad environmental partitioning
into "humid America" and "arid America." Where annual precipitation exceeds 20 inches
(50 centimeters),soils in humid areas tend to be acidic in chemical content, Since crops
(5) do best in soils that ale neither acidic(higher in acid content) nor alkaline(higher in salt
content).fertilization is necessary to achieve the desired level of neutrality between the
two. Arid America’s soils are typically alkaline and must be fertilized back toward
neutrality by adding acidic compounds. Although many of these dryland soils, particularly
in the Great Plains, are quite fertile, European settlers learned over a century ago that
(10) water is the main missing ingredient in achieving their agricultural potential. In the
1970’s, certain irrigation methods were perfected and finally provided a real opportunity
to expand more intensive farming west from the Central Lowland into the drier portions
of the Great Plains. Glaciation also enhanced the rich legacy of fertile soils in the central
United States, both from the deposition of mineral-rich glacial debris left by meltwater
(15) and from thick layers of fine wind-blown glacial material, called loess, in and around the
middle Mississippi Valley.
Natural vegetation patterns could be displayed on a map of North America, but the
enormous human modification of the North American environment in modem times has
all but reduced this regionalization scheme to the level of the hypothetical. Nonetheless,
(20) the humid America-arid America dichotomy is still a valid generalization: the natural
vegetation of areas receiving more than 20 inches of water yearly is forest, whereas the
drier climates give rise to a grassland cover. The forests of North America tent to make
a broad transition by latitude. In the Canadian North, needle-leaf forests dominate, but
these coniferous trees become mixed with broadleaf deciduous trees as one crosses the
(25) border into the Northeast United States As one proceeds toward the Southeast, broadleaf vegetation
becomes dominant. Arid America mostly consists of short-grass prairies or
stepper. The only areas of true desert are in the Southwest.
选项
A、The wide variety of climates
B、Soil types and vegetation patterns
C、Improved irrigation methods and the expansion of agriculture
D、The change in precipitation patterns
答案
B
解析
转载请注明原文地址:https://jikaoti.com/ti/OklYFFFM
0
托福(TOEFL)
相关试题推荐
Youshouldspendabout20minutesonQuestions27-40,whicharebasedonReadingPassage3below.Quie
ChooseTWOletters,A-E.Writethecorrectlettersinboxes7and8onyouranswersheet.WhichTWOpositivefunctionsaboutMin
Youshouldspendabout20minutesonQuestions1-13whicharebasedonReadingPassage1below.Australia’sGrowingDisasterFar
Farmershaveastrongsenseofsolidaritybecause______
Completethesentencesbelow.WriteNOMORETHANTWOWORDSAND/ORANUMBERforeachanswer.Aholedugbyafemalecrocodilein
Completethenotesbelow.WriteNOMORETHANTWOWORDSforeachanswer.TheArgussystemDevelopedbyRo
Choosethecorrectletter,A,BorC.Whatwasthemostdifficultproblemwhenthecompanywasfounded?
LaughterThenatureoflaughterlaughterisa【L31】________process—involvesmovementandsounditiscontrolledbyour【
RiverTurtlesNestinghabitsThearrauturtle’sshellisapproximately【L31】________long.Afemalearraudepositsatleast【L32
(Independencepolitical)ofnewspapers(became)a(commonfeature)of(journalism)intheUnitedStatesofthe1840’sand1850’s
随机试题
地理环境决定着经济制度和文化价值观念。()
A.吞咽时咽部异物感,胃灼热,反酸B.上腹不适,隐痛,嗳气C.进行性吞咽困难D.咽下困难伴进食时或进食后数分钟内食物反流E.咽下困难可突然出现或突然消失反流性食管炎主要表现为
患者食积气滞,脘腹胀满,大便秘结,治疗宜选用
根据中药材中植物药的采收原则,不同药用部位的药材,采收时间不同,其有效成分的种类和含量不同。以下药材需在春末夏初采收的是
【背景资料】某火力发电厂工程由A施工单位承包施工,B监理单位承包工程施工监理工作。经建设单位同意,A施工单位将该电厂烟囱工程的施工分包给C施工单位施工。为了保证烟囱工程施工的顺利进行,在施工准备阶段,C施工单位制定了烟囱工程施工的安全工
下列各项中,不属于2003年《新巴塞尔资本协议》中的“三大支柱”的是()。
请举例论述儿童文学的文体特征。要求举例时准确说明该部儿童文学的名称、作者、相关人物等。
阅读技能、写作技能、运算技能、解题技能等属于_________技能。
(2010—单选—30)在市场经济中,政府往往采用货币和财政政策来调控经济。下列措施中,属于货币政策的是()。
1+3,2+2,1+1,2+3,1+2,2+1,______。
最新回复
(
0
)