新视野大学英语读写教程听力 第三册 te-unit06-b

[-1:-9.00]can be found under the Earth's surface.
[-1:10.00]Petroleum is a valuable resource.
[-1:11.00]Should people use it up to manufacture petrol for automobiles?
[-1:12.00]As people work to control the planet and make life comfortable,
[-1:13.00]are they using up resources that are needed for their survival?
[-1:14.00]11  The Balance of Nature
[-1:15.00]12  All natural systems tend toward balance among opposing factors or forces.
[-1:16.00]Human activities can cause or accelerate
[-1:17.00]permanent changes in natural systems.
[-1:18.00]The smoke of one small fire causes no harm to the environment.
[-1:19.00]Natural cleaning processes can clean the particles of smoke from the air.
[-1:20.00]However, the collective smoke from thousands of factories,
[-1:21.00]over the past two centuries,
[-1:22.00]has caused enormous increases in air pollution levels worldwide.
[-1:23.00]Cleaning this smoke has exceeded the protective ability of natural processes.
[-1:24.00]The forests cannot clean the air fast enough.
[-1:25.00]13  In spite of rapid population increase and industrial growth,
[-1:26.00]some groups of people, often in remote areas,
[-1:27.00]have been able to live in harmony with the planet.
[-1:28.00]These people have not changed their ways of living
[-1:29.00]from the ways of their ancestors.
[-1:30.00]Called native people,
[-1:31.00]they retain the ways of life
[-1:32.00]that have remained unchanged for many generations.
[-1:33.00]Many of their cultural values and ways of life
[-1:34.00]include practices that return resources to the Earth.
[-1:35.00]14  Human population growth is creating food shortages,
[-1:36.00]problems of air quality,
[-1:37.00]and changes in weather patterns.
[-1:38.00]What is destroying rain forests and ruining the land and seas?
[-1:39.00]What causes the acid rain
[-1:40.00]that forms from water passing through polluted air?
[-1:41.00]Why is there the threat of global warming?
[-1:42.00]All these harmful results come from the too much use of resources
[-1:43.00]and the human struggle to control the environment.
[-1:44.00]15  The twentieth century began with powerful countries
[-1:45.00]competing to take advantage of the Earth.
[-1:46.00]As an outcome of their hunger for empires,
[-1:47.00]the Earth was abused.
[-1:48.00]Now people all over the world are living
[-1:49.00]with the problems caused by this abuse.
[-1:50.00]Now that they are no longer ignorant of the causes
[-1:51.00]of hte sickness of our planet,
[-1:52.00]they seek ways to help the Earth,
[-1:53.00]to give back what they take away.
[-1:54.00]Previously, mankind only used the Earth.
[-1:55.00]Now everyone must protect planet Earth,
[-1:56.00]a planet in danger.