英语听力教程第三版(张民伦主编)Unit 1 The Earth at Risk听力原文
firewood and their domestic animals eat all the available plants — and so consequently they have to move south as the Sahara Desert expands further south. I mean, soon the whole of Mali will become a desert. And ... er ... in East Africa: here the grasslands are supporting too many animals and the result is, of course, there's no grass— nothing for the animals to eat. I:Mm, yes, I see. Um ... and the ... the next film deals with North
America?
B:That's right. In the ... er ... USA, as you know, intensive agriculture requires a plentiful supply of rain for these crops to grow, I mean if there isn't enough rain the crops don't grow. And growing crops stabilize soil, without them the top soil just... it just blows away. I mean, this is also true for any region that is intensely farmed — most of Europe, for example. I: And what did you find in South America?
B:In South America (a ... as in Central Africa and Southern Asia) tropical forests are being cut down at an alarming rate. Th ... this is done so that people can support themselves by growing food or to create ranches where cattle can be raised to exp ... to be exported to Europe or America as tinned meat. The problem