首页
登录
职称英语
The wide variety of climates in North America has helped spawn a complex
The wide variety of climates in North America has helped spawn a complex
游客
2024-01-05
7
管理
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://tihaiku.com/zcyy/3334799.html
相关试题推荐
ChooseTWOletters,A-E.WhichTWOsourcesoffundinghelpedbuildthefacility?
Choosethecorrectletter,A,BorC.[br]IfAmericanhadanextradayper-week
Choosethecorrectletter,A,BorC.[br]Americanboysdropoutofschoolata
Choose.TWOletters,A-E.WhichTWOsourcesoffundinghelpedbuildthefacility
Choose.TWOletters,A-E.WhichTWOsourcesoffundinghelpedbuildthefacility
Composerstodayuseawidervarietyofsoundsthaneverbefore,includin
Thecommonbarnowl,oneoftenspeciesofbarnowlsfoundinNorthAmerica,is
TheMoon,whichhasundergoneadistinctandcomplexgeologicalhistory,p
TheNorthAmericanReview,a(magazinewas)first(published)in1815,wasoneo
IntheNorthAmericancolonies,redware,asimplepotteryfiredatlow
随机试题
他们是一对新婚夫妇。Theyareanewlymarriedcouple.原译的新婚夫妇译作anewlymarriedcoupleofhus
A.associatedB.completedC.dailyD.dataE.disharmonyF.e
Thesegoodsaresoldatreducedprices,________.A、thedefectsarepointedoutt
企业收入总额中的下列收入不属于不征税收入的事()。A.财政拨款 B.国有企业
下列描述不属于功血的是A.萎缩型子宫内膜 B.增生期子宫内膜 C.不典型增生
外源性凝血系统最常用的筛选试验是A.纤维蛋白原测定B.APTTC.TTD.CTE
可使尿液呈现红色的药物是()A.顺铂 B.柔红霉素 C.依托泊苷
《中华人民共和国药典》中规定,称取"2.00g''系指A.称取重量可为1~3g
和患者非正式交谈的主要特点是()。A.谈话环境安静 B.谈话主题明确 C.交
“十一五”时期,推进我国城镇化需要遵循的原则是() A.节约土地B.合理
最新回复
(
0
)