U13   New Sciences and Technology

科普新知识

Finding the Most Effective and Economical Fuel for Cars

Reading Comprehension

       (包括“答案与题解”)

       Notes

       课文参考译文

       练习

         ●Cloze

●Reading Passages(包括“疑难长句翻译与注解”)

         ●Translation

●Writing(包括“审题指导”)

Finding the Most Effective and Economical Fuel for Cars

While some researchers concentrate on the car and improving its systems and materials, others focus on the fuel that feeds the car. On at least one occasion, car improvements and fuel refinements went hand in hand. When catalytic converters were developed, the petroleum industry had to make gasoline lead-free. Leaded gasoline produces emissions containing lead, which coats the metals in the converter, rendering them ineffective. Because lead has been linked to cancer and can cause nervous system damage in children, lead-free gasoline was an important development against automobile pollution.

Researchers continue to search for ways to make better gasoline. Refining crude oil to produce gasoline involves heating the oil and drawing off various types of hydrocarbons as they evaporate. Some hydrocarbons are lightweight molecules that evaporate easily. Others are heavier, have a tendency to form deposits and particulates, and may be cancer-causing.

Petroleum companies can create gasolines that pollute less by using more hydrocarbons from the middle of the weight spectrum—those that are neither very light nor very heavy. Refiners can also break down or “crack” some of the heavier hydrocarbons to yield lighter compounds. Some gasoline additives include oxygen atoms in their structure. This helps promote more complete fuel combustion.

Researchers are also investigating fuels other than gasoline. Methanol emits smaller quantities of pollutants normally associated with gasoline combustion. But it has less potential energy than does gasoline, and it is more difficult to ignite. Methanol also can corrode many of the metals. Finally, methanol produces a harmful compound that irritates the eyes, nose, and throat, and which is thought to cause cancer. On the positive side, methanol burns more completely than does gasoline, and when mixed with 15 percent gasoline to form a fuel called M-85, it achieves satisfactory starting performance. A “flexible fuel” engine can run on either gasoline or methanol or a combination of both. Special sensors determine the type of fuel in use and relay this information to the central computer system.

Natural gas is another abundant fuel that experts consider an alternative to gasoline. It is composed mainly of methane gas and is cheaper and much cleaner than gasoline. This fuel’s major drawback is that unlike gasoline and methanol, it is not available as a liquid at normal air temperatures and pressures. Natural gas must be carried in a pressurized tank, or, as a liquid, in an insulated tank—unfamiliar additions to a car’s design that consumers may reject. Refueling with natural gas could take up to several hours.

Some scientists are interested in hydrogen as the fuel of the future. Hydrogen burns much more cleanly than do other fuels and is easy to produce. But complex technical problems must be solved before it can be widely used in cars.

Electric vehicles are quiet and virtually emission-free.  However, the batteries from which they draw energy usually contain harmful chemicals, which become pollutants when the batteries are disposed of. Today’s electric cars cannot go as far or as fast as gasoline-driven vehicles because the battery does not offer the same amount of energy as does gasoline combustion. Furthermore, the battery must be recharged regularly, and the energy to do this comes from power plants that are also a source of pollution. Nevertheless, electric vehicles are the likely choice for meeting zero-emission laws that have been established in some areas, such as California.

The ongoing search for ways to make cars cleaner poses a demanding challenge to engineers, as well as chemists, materials scientists, and technicians. The widespread research reflects our new heightened concerns for the environment along with our old desire to maintain the freedom of movement that the automobile has brought to the developed world.

1. It is implied in the first paragraph that refined fuel may not produce the desired result .

 ［A］ without the improvement on the car itself

 ［B］ without the addition of lead

 ［C］ because it is still polluting

 ［D］ when it is too expensive for drivers

2. Lead-free gasoline represented a leap in the search for cleaner fuel because .

 ［A］ it is less harmful to health

 ［B］ it makes the catalytic converter work more effectively

 ［C］ it is nonpollutant to the environment

 ［D］ it went hand in hand with car improvements

3. Which of the following fuels is the most effective in terms of the amount of energy it generates?

 ［A］ The battery.                           ［B］ Gasoline.

 ［C］ Methanol.                                                 ［D］ Natural gas.

4. Which of the following fuels is the cleanest?

 ［A］ Gasoline.                            ［B］ Methanol.

 ［C］ Hydrogen.                                                ［D］ Natural Gas.

5. In their search for future fuels, scientists have always in mind the goal of finding .

 ［A］ the most economical and easily-produced fuel

 ［B］ the most extensively applicable fuel

 ［C］ the fuel that gives cars the utmost performance

 ［D］ a nonpolluting and the most effective fuel

答案与题解

1.［A］  

本段第一、二句都提到了燃料的改进和汽车的改进必须同步，其他三句从反面说明了同步改进的必要性。

2.［A］  

根据第一段，含铅汽油导致癌症，对孩子的神经系统有害，所以，无铅汽油在防止汽车废气污染上是一大进步。

3.［B］  

参阅第四段第三句、第七段第三句。

4.［C］  

参阅第六段第二句。

5.［D］  

主要参阅文章最后一段。最后一段中提到对环境的关注，所谓关心环境，即不污染环境。另外，在讨论每一种燃料时，几乎都提到了它是否产生污染，是否有效、实用。

Notes

1. 第二段最后一句中particulates是“微粒”的意思。

2. 第三段第一句中weight spectrum是“重量谱”的意思。

3. 第五段第四句是一个简单主从复合句。 句架是Natural gas must be carried in...tank, or， ...， in an...tank—unfamiliar...design that...。 句中破折号后的内容是说明insulated tank的；that引导定语从句，修饰design。

4. 第七段第二句是一个简单主从复合句。 句架是...， the batteries from which...contain...chemicals, which...when...。句中from which引导定语从句， 修饰batteries; which引导非限制性定语从句修饰前面整个句子；when在非限制性定语从句中引导时间状语从句。

课文参考译文

为汽车找到最有效和最经济的燃料

虽然一些研究人员集中精力研究汽车并改进汽车系统和材料，但是其他人的研究重点放在汽车的燃料上。至少在一个场合，改进汽车和提炼燃料是同时进行的。在研制出催化转化器之后，石油工业必须使汽油变成无铅汽油。含铅汽油排放的废气中有铅，会使转化器中的金属涂上一层膜，导致这些金属失效。由于铅已与癌症联系起来并能引起儿童神经系统损伤，因此无铅汽油是针对汽车污染的一项重要发展。

研究人员继续寻找改善汽油的办法。提炼原油以生产汽油涉及给石油加热并在石油挥发过程中提取各种碳氢化合物。有一些碳氢化合物是容易挥发的轻量分子，其他碳氢化合物重一些，有形成沉积物和微粒的趋势，并可能引起癌症。

石油公司通过更多使用重量等级居中的碳氢化合物——既不是很轻也不是很重的碳氢化合物——就能创造出污染较少的汽油。提炼厂也能分解或“裂化”较重的碳氢化合物以产生较轻的化合物。一些汽油添加剂在其结构中含有氧原子，这有助于促使燃料燃烧更完全。

研究人员还在调查除汽油之外的其他燃料。甲醇排放的污染物数量较少，这些污染物通常与汽油燃烧有关。但是甲醇的潜能比汽油少，而且甲醇更难点燃。甲醇也能腐蚀许多金属。最后，甲醇产生一种刺激眼睛、鼻子和咽喉的有害化合物，被认为能引起癌症。从积极方面来说，甲醇比汽油燃烧得更完全，在与15％的汽油混合成一种叫M-85的燃料时，这种新燃料的启动性能令人满意。一种使用“灵活燃料”的引擎既能烧汽油也能烧甲醇，或者烧两种燃料的混合物。特殊传感器能决定使用哪一种燃料，并能把这个信息传达到中央电脑系统。

天然气是专家们认为能代替汽油的另一种储量丰富的燃料。天然气主要由甲烷构成，比汽油便宜，也比汽油清洁得多。这种燃料的主要缺点是，不像汽油和甲醇，天然气在正常的气温和气压下无法以液态存在。天然气必须装在压力罐中，或者液态时要装在绝缘罐中——这是消费者可能拒绝的汽车设计之外的陌生附加物。加注天然气可能需要几个小时的时间。

一些科学家对把氢气作为一种未来的燃料很感兴趣。氢燃烧比其他燃料燃烧都更清洁，而且容易生产。但是在氢气能广泛用于汽车之前，必须先解决复杂的技术问题。      电车安静，而且实际上不排放任何废气。但是，电车用以获取能源的电池通常含有有害的化学物质。在电池被抛弃后，这些化学物质就变成了污染物。由于电池供应的能量不如汽油燃烧产生的能量大，因此今天的电车不可能像汽油驱动的车辆跑得那样远或那样快。此外，电池必须经常充电，充电所需的能源来自发电厂，而发电厂本身也是污染源。尽管如此，在像加利福尼亚这样一些已制定零排放法的地区，电车是满足零排放法要求的可能选择。

设法使汽车更清洁的持续不断的探索是对工程师以及化学家、材料科学家和技师提出的严峻挑战。我们过去的愿望是维护汽车给我们发达的世界带来的行动自由。而目前这种广泛探索同我们过去的愿望一起，反映出我们对环境的强烈的新关注。