首页
登录
职称英语
[originaltext] Today, I’d like to talk about some of the changes land can un
[originaltext] Today, I’d like to talk about some of the changes land can un
游客
2025-02-09
42
管理
问题
Today, I’d like to talk about some of the changes land can undergo, specifically desertification, that’s the process through which land becomes part of a desert. Now a desert is defined as a place that receives a certain maximum amount of rainfall. But you may not know that it usually takes more than just a lack of water to turn productive land into a desert. There are several specific human activities that when combined with a lack of rainfall encourage desertification. For example, over cultivation, growing more crops than soil can support. The soil loses its nutrients, so it needs either to be fertilized or to be left unused for at least a season. But if neither of these things happens, if these nutrients in the soil don’t get replaced, the damaged soil stops producing. Another cause of desertification is overgrazing. That’s when the grasses and trees and shrubs of an area are expected to feed more animals than they reasonably can. Too many animals eating in the same area will kill the vegetation. And because it’s the roots of this vegetation that hold much of the soil together, when too much of the vegetation dies, the soil erodes. But maybe the most ironic example of human behavior that can lead to desertification is irrigation. It may seem to run counter to common sense to say that introducing water into an area can cause it to become more like a desert. But there are plenty of bad irrigation practices that do just that. Bringing in too much salty water and then not providing adequate drainage for it will fill the soil with salt, and turn the area into a desert.
选项
A、Settlement patterns in desert.
B、Causes of desertification.
C、Plant adaptation to desert conditions:
D、Regions most affected by desertification.
答案
B
解析
What?is?the?main?topic?of?the?talk?
转载请注明原文地址:https://tihaiku.com/zcyy/3949427.html
相关试题推荐
[originaltext]AsIamsureyouareaware,historyisfullofpeoplewhower
[originaltext]Today,I’dliketotalkaboutsomeofthechangeslandcanun
[originaltext]Today,I’dliketotalkaboutsomeofthechangeslandcanun
[originaltext]M:Oneofthemostcommonquestionsweaskaboutpeople’sbehavio
[originaltext]M:Oneofthemostcommonquestionsweaskaboutpeople’sbehavio
[originaltext]M:Iseeyoustillgotallyoursuitcaseswithyoutoo.Wemusth
[originaltext]M:Iseeyoustillgotallyoursuitcaseswithyoutoo.Wemusth
[originaltext]Inordertodiagnoseandtreatabnormalbehavior,wehaveto
[originaltext]Inordertodiagnoseandtreatabnormalbehavior,wehaveto
[originaltext]Wearegoingtotalktodayaboutthemoon,ourmoon.Firstof
随机试题
Targetyesterday【C1】______WallStreetexpectationswhenit【C2】______a21.1perce
有效氧化钙测定中,酚酞指示剂加入试样溶液中,溶液呈()色。A.黄 B.橙
患者,女,66岁,下唇部肿物3年,诊断为"下唇鳞状细胞癌",行"肿物扩大切除术"
下列哪项不是母乳喂养的优点A.钙磷比例适当(2:1),较少发生低钙血症 B.含
三、2016年1-7月,同城、异地、国际/港澳台快递业务量分别占全部快递业务量的
关于阴道的描述,正确的为A.阴道腔呈上窄下宽 B.阴道粘膜无周期性变化 C.
隆庆年间,与明朝廷订立和议的蒙古鞑靼部首领是( )。A.也先 B.阿鲁台
特雷诺指数是()。A:连接证券组合与无风险资产的直线的斜率B:连接证券组合与无
(2018年真题)下列各项中,属于环境保护税征税范围的有( )。A.煤矸石
(2020年真题)劳动强度是以作业过程中人体的能耗量、氧耗、心率、排汗率等指标为
最新回复
(
0
)