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
Environmental Science Listen to Track 91.
Environmental Science Listen to Track 91.
admin
2014-09-29
15
问题
Environmental Science
Listen to Track 91.
Environmental Science
Narrator
Listen to part of a lecture in an environmental science class.
Professor
OK, now let’s talk about another environmental concern—soil erosion. It’s a major problem, all around the world. Sometimes erosion damages soil so severely that the land can no longer be cultivated and it’s just abandoned. That happened in a big way right here in the United States. Some of you have probably read the novel The Grapes of Wrath. And maybe you remember that the story took place in the 1930s, during the time of what was called the Dust Bowl.
Dust Bowl is a term we use to describe an ecological and human disaster that took place in the southern Great Plains region. For nearly eight years, dust and sand blew across the area and covered everything. It was so bad it even made breathing and eating difficult. . . and farmers could only look on helplessly as their crops were destroyed and the land .. . and their lives ... ruined.
Now, there’d always been droughts and strong winds in that region. But that was OK because the native grasses had deep roots in the ground that were able to hold the soil in place. So the wind wasn’t able to, you know, erode the soil too badly. This changed, though, between 1900 and 1930. Agriculture was expanding rapidly then, and lots of farmers in the southern Great Plains wanted to grow wheat and other crops they could sell for cash—uh, crops that would be profitable. So they ripped up much of the grassland to plant these crops like wheat, which don’t hold the soil down nearly as well. At the same time, livestock—uh, cattle, too many of them—were feeding on grasses in the area and damaging a lot of the grassland. So these animals caused even more erosion of the soil.
It didn’t help that many of the actual owners of the land were not living anywhere near the area—a lot of the landowners lived way back east, and rented out the land to local people who lived on the land and worked on it, but, um, didn’t have much reason to take really good care of it. I mean, it wasn’t their land, right? The tenant farmers weren’t really interested in conserving someone else’s soil—not for the long term, anyway.
Also, some thought the land couldn’t really be damaged—you know, that the soil was so rich and deep that... it didn’t matter if the topsoil, the soil on the surface, blew away. They thought they could just plow up more. But they were wrong. Good top-soil takes a long time to form—it can literally take thousands of years to create good topsoil that will grow vegetation—and a very short time to ruin it. So after only a few years of excessive plowing, the land pretty much couldn’t be farmed anymore. And people moved on to other places and let the old areas just sit there. And when they didn’t plant anything on that land, that made it vulnerable to even more erosion. So it was kind of a vicious cycle, you could say.
Another problem, ironically, was that advances in technology were actually destroying the land, instead of improving it. A lot of farmers were using huge new tractors that dug deep into the ground and tore up a lot of the soil.
And then, of course, there was the weather. You know, when people look back on the Dust Bowl era, they tend to blame the drought—the lack of rain between 1934 and 1937. We can’t ignore the drought—I mean, it was the worst on record at the time and did help bring on this disaster. But—without the soil destruction—the drought alone wouldn’t have resulted in the devastation we call the Dust Bowl. It was poor farming techniques that made that happen.
Since then, though, we’ve paid more attention to trying to prevent a future Dust Bowl. One thing Congress did was enact a massive government effort to improve soil conservation, called the Soil Erosion Act. Under this law, large stretches of land in the southern Great Plains were identified as being at risk for erosion and were taken out of production and turned into permanent grassland. What that did—by protecting the land from excessive farming—was to stabilize the soil. Also, the Soil Erosion Act helped educate farmers to practice better soil conservation techniques, like reducing how often they plowed and using better equipment that would, you know, minimize damage to the soil structure.
Narrator
Listen again to part of the lecture. Then answer the question.
Professor
A lot of the landowners lived way back east, and rented out the land to local people who lived on the land and worked on it, but, um, didn’t have much reason to take really good care of it. I mean, it wasn’t their land, right?
Narrator
Why does the professor say this:
Professor
I mean, it wasn’t their land, right?
选项
A、To ask the students for their opinions
B、To express uncertainty about a historical situation
C、To emphasize a point he has just made
D、To correct an earlier statement
答案
C
解析
转载请注明原文地址:https://kaotiyun.com/show/OTfO777K
0
托福(TOEFL)
相关试题推荐
Completethetablebelow.WriteNOMORETHANTHREEWORDSAND/ORANUMBERforeachanswer.
Completethenotesbelow.WriteNOMORETHANTWOWORDSforeachanswer.NecessaryimprovementstotheexistingSelf-
Completethenotesbelow.WriteNOMORETHANTWOWORDSforeachanswer.NecessaryimprovementstotheexistingSelf-
Completetheformbelow.WriteONEWORDAND/ORANUMBERforeachanswer.
Labelthediagrambelow.ChooseTHREEanswersfromtheboxandwritethecorrectletter,A-E,nexttoquestions11-13.Aelectri
Completethenotesbelow.WriteONEWORDONLYforeachanswer.NotesonCustomer’sInformationExampleAnswerInforma
Completethetablebelow.WriteNOMORETHANTWOWORDSAND/ORANUMBERforeachanswer.Talkingaboutthehistoryofbikes
Listentothedirectionsandmatchtheplacesinquestions11-15totheappropriateplaceamongA-Eonthemap.Cafe
Listentothedirectionsandmatchtheplacesinquestions11-15totheappropriateplaceamongA-Eonthemap.InternetUnit
Completethesentencesbelow.WriteNOMORETHANTWOWORDSforeachanswer.Duringtheflight,______facilitieshelpedhimdistr
随机试题
不是残疾人口腔保健特殊点的是
从中药的水提液中萃取亲水性成分,可选用的溶剂是
男,36岁。开始上腹部疼痛,6个小时后出现右下腹疼痛,体温37.6℃,白细胞12×109/L,中性粒细胞0.73。首先考虑其患有
持续胃肠减压时间较长时,应加强的护理项目有
根据《宪法》的规定,下列哪些选项是正确的?(2012年卷一60题,多选)
承运人制定特种运价的初衷主要是考虑()。
下列各项关于现金折扣会计处理的表述中,正确的是()。
波长为600nm的平行光垂直照射在12cm长的两玻璃片上,两玻璃片一端相互接触,另一端夹一直径为d的金属丝。若测得这12cm内有N=141条明纹,则金属丝的直径为()。
“百年大计,教育为本”,体现了教育在社会主义现代化建设中的()地位。
以下选项中,认为行政法规同宪法或者法律相抵触,有权提出审查要求的是()
最新回复
(
0
)