首页
登录
职称英语
The cause of the decline of North Africa is popularly attributed to climatic
The cause of the decline of North Africa is popularly attributed to climatic
游客
2023-07-22
20
管理
问题
The cause of the decline of North Africa is popularly attributed to climatic changes, the theory being that the area became hotter and drier and the people were forced to abandon a thriving civilization. However, some geologists, after carefully weighing the evidence, have challenged the conclusion that the climate has changed in any important way since Roman tithes. Although climatological factors may also have contributed, it was man who destroyed the balance of nature responsible for maintaining soil fertility and moisture.
Why is it that under certain circumstances, the plant cover is unable to regenerate itself, thus setting the stage for serious erosion(腐蚀)? To answer this question, let us take an extreme example, the destruction of tropical rain forests. In general, the equatorial(赤道附近的)soil is poor: forests can exist in these regions only because they are part of a balanced cycle. All that the forest produces is returned to the forest. The organic matter that falls from the trees constitutes the humus(腐殖土)that the forest requires. When people cut down all the trees to make room for crops, the soil is laid bare and, deprived of shade, heats up. An increase in soil temperature increases the rate of decomposition(分解)of organic matter. Organic nitrogen(氮)is converted into soluble ammonia(氨)and nitrates(硝酸盐), which the rains quickly leach(沥滤,溶滤)away. It has been calculated that a rise in temperature from 77 to 78.8 may increase the loss of nitrogen by fifteen to twenty pounds per acre per year. With the fertility of soil destroyed, an irreversible change from forest to desert can be initiated. [br] Increase in the temperature of tropical soil ______.
选项
A、might cause the overflow of flood
B、may lead to the loss of organic nitrogen in it
C、will produce a great deal of organic nitrogen
D、is harmless to the growth of rain forests
答案
B
解析
这三句话表明温度升高会导致大量有机氮的流失。选项B符合原文意思。
转载请注明原文地址:https://tihaiku.com/zcyy/2858472.html
相关试题推荐
Mysuccess____________(从很大程度上来说)shouldbeattributedtomycoworkers.toala
[originaltext]CamerooninWestAfricaisanationof24separatelanguages
ThecauseofthedeclineofNorthAfricaispopularlyattributedtoclimatic
ThecauseofthedeclineofNorthAfricaispopularlyattributedtoclimatic
ThecauseofthedeclineofNorthAfricaispopularlyattributedtoclimatic
Internetuseappearstocauseadeclineinpsychologicalwell-being,accordi
Internetuseappearstocauseadeclineinpsychologicalwell-being,accordi
Internetuseappearstocauseadeclineinpsychologicalwell-being,accordi
Internetuseappearstocauseadeclineinpsychologicalwell-being,accordi
Internetuseappearstocauseadeclineinpsychologicalwell-being,accordi
随机试题
Diamonds,sparklingunderanAfricansun,haveanattractioncommensurate(相称
[originaltext]M:Helloandwelcometotoday’sshow,Shirley’sGarden.Today,we
Comparedwithelderlyparentsandadultchildreninfiveotherindustrialize
Itcanbeinferredfromthefirstparagraphthat______.[br]Thesalesofrobot
乙企业目前的流动比率为2,若赊购材料一批,将会导致乙企业( )。A.速动比率降低
孕妇,28岁,孕35周,子痫前期,患者突发腹痛,4小时后胎心消失,宫底明显升高,
A.seeB.resembleC.showD.look
电流互感器是把大电流变为小电流的设备,又称变流器。
关于可行性研究及其报告应达到的深度要求的说法,正确的是()。A.可行性研究
慢性细菌性痢疾迁延型是指病情迁延不愈,病程至少超过( )。A.150天 B.
最新回复
(
0
)