The earth's biosphere (the surface layer of the planet and the surrounding atmosphere) provides the land, air, water, and energy necessary to sustain life. This life-support system is a plex, interdependent one in which energy from the sun is changed into food for humans. The entire system depends on the sun, reasonably moderate temperature, and enough supplies of oxygen, pure water, and fertile soil.
Since the earth's creation millions of years ago, the ecosystem has worked as an interdependent system relatively undisturbed by outside forces. But recently, especially since the Industrial Revolution, human beings have begun to disturb the balance of nature. Natural resources have been severely depleted (消耗) (forests have been destroyed, fertile land worn away, water polluted, and minerals used up), and the life-support system of air, water, and land has been poisoned by a variety of waste products and chemicals.
The degree of these problems was noted in a report by the U.N. Developing Council on Environmental Quality. This report predicted that if present trends continue, the world will be more crowded and polluted and less stable ecologically and politically than the world we live in now.
The twin problems of resource shortages and pollution are caused by three social forces. First, the tremendous increase in population growth constantly increases the demand for food, energy, and other products. As the current population continues to increase, the stress on an already overburdened environment will be increased．A second source of the problem is the concentration of people in urban areas, where the ecosystem simply cannot absorb their waste products. Finally, environmental problems are worsened as more and more nations move toward modem development: an increased reliance on modern technology. As these nations bee more technological, they will consume more energy, deplete more natural resources, and create more waste products than the biosphere can absorb.
【小题1】The life-support system is posed of .A．air, water and landB．the earth, the sun and energyC．food, land and energyD．food, energy and the sun【小题2】The life-support system .A．change energy from the sun into food for humansB．depends on the sun for enough supplies of air, water and landC．exists in the surface layer of the earth and the surrounding atmosphereD．is a plex but independent system【小题3】The life-support system has been badly damaged by . A．natural forcesB．human activitiesC．social movements D．political changes【小题4】The passage mainly talks about .A．the effects of Industrial Revolution on human beingsB．the importance of life-support system to human beingsC．the significance of balance of natureD．the destruction of life-support system and its causesA
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(答案→)A
解析：这是一篇环保类短文，本文讲叙的是：地球的生物圈提供了一种由土地、空气、水和能量组成的生命支持系统，这一系统将太阳能转化为人类的食物。
【小题1】细节理解题。根据文章开头前两句，（the land, air, water, and energy necessary to sustain life）生命支持系统是由土地、空气、水和能量组成的。
【小题2】细节理解题。根据第一段第二、三句，（The entire system depends on the sun）生命支持系统是一个复杂的相互依赖的系统，在此系统中太阳能被转化为人类的食物。
【小题3】归纳概括题。在第二段中提到，尤其工业革命后，人类开始扰乱自然界的平衡，自然资源大量枯竭，主要是通过排放废产品和化学物质。所有上述行为可归结为human activities。
【小题4】主旨大意题。文章开头先讲了生命支持系统是什么，然后又讲了由于人类行为而造成的问题以及造成这些问题的三种社会力量，所以D项能概括这几层意思。