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  3. My topic today is "The Car and Air pollution. " In particular, I want firstly to discuss the ways in which the car causes air po

My topic today is "The Car and Air pollution. " In particular, I want firstly to discuss the ways in which the car causes air po

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问题     My topic today is "The Car and Air pollution. " In particular, I want firstly to discuss the ways in which the car causes air pollution; and secondly, how we can control or reduce air pollution from the car.
    First, then, how does the car cause air pollution? 【T1】What happens is that the car’s internal combustion engine is a kind of chemical factory on a small scale. It uses a mixture of petrol and air, and this mixture explodes and burns, to produce the energy which propels the car. 【T2】But while this is happening, many complicated chemical reactions are taking place. In particular, part of the petrol-air mixture is not completely burned up, and so the exhaust gasses from the engine contain some very dangerous chemicals, such as carbon monoxide, nitrogen oxides, lead and hydrocarbons.
    This is the situation, then, and it’s going to get much worse, unless we do something about it. So, let’s focus our attention now on ways of controlling or reducing the amount of air pollution caused by the car.
    First, we can discourage the use of cars. For example, we can put higher taxes on petrol and on cars themselves-especially the larger ones that use a lot of petrol.
     【T3】Second, we can encourage alternative methods of transport both between and within urban areas. For instance, we can make train and bus services cheaper and more convenient. And we can build a mass transit system in large cities, particularly an underground railway system such as those in London, New York, Moscow and Tokyo.
    Next, we can use a different and cleaner fuel for the internal combustion engine with other designs.
    Fourth, we can replace the present internal combustion engine with other designs. There are several possibilities being researched at present, such as electric, gas turbine, and "steam" engines. However, each of these engine designs has its own disadvantages.
     【T4】Last but not the least, we are trying to control the emissions from the internal combustion engine much more strictly. This, for example, is a catalytic converter, which converts the most dangerous ingredients of the car exhaust into water and harmless gases.
    As I’m sure you can see, there are problems with each of these ways; but at least they’re a step in the right direction. Probable the best answer is a synthesis of all five.
【T2】
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答案汽油跟空气燃爆的同时也发生了许多复杂的化学反应。尤其糟糕的是，由于汽油加空气的混合物未能全部完全燃烧，引擎排出的各种废气含有一些十分有害的化学物质。
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