202 Useful Exercises for IELTS Side2-01-AudioTrack01

　　 Narrator: Exercise 3.9. Lecture 3:
       Electric cars? Solar-powered buses? When most people imagine solutions to the problems of city air pollution they probably think of electricity and solar power. But the problem with an electric car is that the electrical energystored within the batteries has to be first produced by conventional means such as burning coal, which creates thevery problem the car is supposedly designed to avoid. Even the battery disposal is an environmental hazard. Asfor solar power, at present the solar panels that catch the sunlight are twice as big as the cars they power. Andspeeds of ten kilometres an hour are hardly practical. What is required is a safe, cheap and highly efficient enginethat produces fewer major air pollutants¹ and only in small quantities. You may be surprised that the answer hasbeen with us for quite some time.
The probable solution to city air pollution is a concept for an engine that was first proposed by a French scientistin 1824 and later designed and patented by a German refrigeration engineer in 1892, whose name was RudolphDiesel. His design for an engine that would produce more energy output but burn less fuel became known as thediesel engine. Most people think of diesel² engines as being efficient and cheaper to run but smelly and rather noisy.
It is true that the black soot³ emitted from the exhausts of diesel lorries does not naturally lead us to conclude thatthe diesel engine can eradicate⁴ air pollution, but, contrary to popular belief, they emit far fewer of all the majorair pollutants than petrol-driven engines, except for nitrogen oxides and black soot. However, soot can be trapped,and already new diesel engines are under development, being redesigned to burn diesel fuel in such a way thatthe nitrogen oxide⁵ gases are released into the air as harmless nitrogen and oxygen.
In fact, if all cars were running on diesel fuel, air pollution in major cities would disappear overnight. Why thenhas it taken this long to do something about it? The problem is that the disadvantages of diesel engines, whichinclude greater noise and vibration⁶ as well as taking longer to start up, have meant that car manufacturers havebeen reluctant to invest in production of more expensive diesel-powered cars - afraid that customers would notpurchase their products. Fortunately, new technology is ensuring that diesel-powered engines become lean, cleanand mean. It might not be long before city smog is but a distant memory.

1 pollutants   

污染物质（尤指工业废物）( pollutant的名词复数 )

参考例句：

• Pollutants are constantly being released into the atmosphere. 污染物质正在不断地被排放到大气中去。
• The 1987 Amendments limit 301(g) discharges to a few well-studied nonconventional pollutants. 1987年的修正案把第301条（g）的普通排放限制施加在一些认真研究过的几种非常规污染物上。 来自英汉非文学 - 环境法 - 环境法

2 diesel   

n.柴油发动机，内燃机

参考例句：

• We experimented with diesel engines to drive the pumps.我们试着用柴油机来带动水泵。
• My tractor operates on diesel oil.我的那台拖拉机用柴油开动。

3 soot   

n.煤烟，烟尘；vt.熏以煤烟

参考例句：

• Soot is the product of the imperfect combustion of fuel.煤烟是燃料不完全燃烧的产物。
• The chimney was choked with soot.烟囱被煤灰堵塞了。

4 eradicate   

v.根除，消灭，杜绝

参考例句：

• These insects are very difficult to eradicate.这些昆虫很难根除。
• They are already battling to eradicate illnesses such as malaria and tetanus.他们已经在努力消灭疟疾、破伤风等疾病。

5 oxide   

n.氧化物

参考例句：

• Oxide is usually seen in our daily life.在我们的日常生活中氧化物很常见。
• How can you get rid of this oxide coating?你们该怎样除去这些氧化皮？

6 vibration   

n.颤动，振动；摆动

参考例句：

• There is so much vibration on a ship that one cannot write.船上的震动大得使人无法书写。
• The vibration of the window woke me up.窗子的震动把我惊醒了。