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It can be inferred from the passage that a vehicle specifically designed to use methanol,
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Although recent years have seen substantial reductions in noxious pollutants from individual motor vehicles, the number of such vehicles has been steadily increasing. Consequently, more than 100 cities in the U. S. still have levels of carbon monoxide, particulate matter, and ozone that exceed legally established limits. There is a growing realization that the only effective way to achieve further reduction in vehicle emissions — short of a massive shift away from the private automobile — is to replace conventional diesel fuel and gasoline with cleaner-burning fuel such as compressed natural gas, liquefied petroleum gas, ethanol, or methanol.
All of these alternatives are carbon-based fuels whose molecules are smaller and simpler than those of gasoline. These molecules burn more cleanly than gasoline, in part because they have fewer, if any, carbon-carbon bonds, and the hydrocarbons they do emit are less likely to generate ozone. The combustion of larger molecules, which have multiple carbon-carbon bonds, involves a more complex series of reactions. These reactions increase the probability of incomplete combustion and are more likely to release uncombusted and photochemically active hydrocarbon compounds into the atmosphere. On the other hand, alternative fuels do have drawbacks. Compressed natural gas would require that vehicles have a set of heavy fuel tanks — a serious liability in terms of performance and fuel efficiency — and liquefied petroleum gas faces fundamental limits on supply.
Ethanol and methanol, on the other hand, have important advantages over other carbon-based alternative fuels: they have a higher energy content per volume and would require minimal changes in the existing network for distributing motor fuel. Ethanol is commonly used as a gasoline supplement, but it is currently about twice as expensive as methanol, the low price of which is one of its attractive features. Methanol's most attractive feature, however, is that it can reduce by about 90 percent the vehicle emissions that form. ozone, the most serious urban air pollutant.
Like any alternative fuel, methanol has its critics. Yet much of the criticism is based on the use of "gasoline alone" vehicles that. do not incorporate even the simplest design improvements that are made possible with the use of methanol. It is true, for example, that a given volume of methanol provides only about one-half of the energy that gasoline and diesel fuel do: other things being equal, the fuel tank would have to be somewhat larger and heavier. However, since methanol-fueled vehicles could be designed to be much more efficient than "gasoline alone" vehicles fueled with methanol, they would need comparatively less fuel. Vehicles incorporating only the simplest of the engine improvements that makes methanol feasible would still contribute to an immediate lessening of urban air pollution.
The author is primarily concerned with ______.
People have been painting pictures for at least 30,000 years. The earliest pictures were painted by people who hunted animals. They used to paint pictures of the animals they wanted to catch and kill. Pictures of this kind have been found on the walls of caves in France and Spain. No one knows why they were painted there. Perhaps the painters thought that their pictures would help them to catch these animals. Or perhaps human beings have always wanted to tell stories in pictures.
About 5,000 years ago, the Egyptians and other people in the Near East began to use pictures as kind of writing. They drew simple pictures or signs to represent things and ideas, and also to represent the sounds of their language. The signs these people used became a kind of alphabet.
The Egyptians used to record information and to tell stories by putting picture writing and pictures together. When an important person died, scenes and stories from his life were painted and carved on the walls
of the place. where he was buried. Some of these pictures are like modern comic strip stories. It has been said that Egypt is the home of the comic strip. But, for the Egyptians, pictures still had magic power. So they did not try to make their way of writing simple. The ordinary people could not understand it.
By the year 1,000 BC, people who lived in the area around the Mediterranean Sea had developed a simpler system of writing. The signs they used were very easy to write, and there were fewer of them than in the Egyptian system. This was because each sign, or letter, represented only one sound in their language. The Greeks developed this system and formed the letters of the Greek alphabet. The Romans copied the idea, and the Roman alphabet is now used all over the world.
These days, we can write down a story, or record information, without using pictures. But we still need pictures of all kinds: drawing, photographs, signs and diagrams. We find them everywhere: in books and newspapers, in the street, and on the walls of the places where we live and work. Pictures help us to understand and remember things more easily, and they can make a story much more interesting.
Pictures of animals were painted on the walls of caves in France and Spain because ______.
People in the United States in the nineteenth century were haunted by the prospect that unprecedented change in the nation's economy would bring social chaos. In the years following 1820 after several decades of relative stability the economy entered a period of sustained and extremely rapid growth that continued to the end of the nineteenth century. Accompanying that growth was a structural change that featured increasing economic diversification and a gradual shift in the nation's labor force from agriculture to manufacturing and other nonagricultural pursuits.
Although the birth rate continued to decline from its high level of the eighteenth and early nineteenth centuries the population roughly doubled every generation during the rest of the nineteenth century. As the population grew, its make up also changed. Massive waves of immigration brought new ethnic groups into the country. Geographic and social mobility — downward as well as upward — touched almost everyone. Local studies indicate that nearly three quarters of the population in the North and South, in the emerging cities — the Northeast and in the restless rural counties of the West — changed their residence each decade. As a consequence, historian David Donald has written, "Social atomization affected every segment of society," and it seemed to many people that "all the recognized values of orderly civilization were gradually being eroded.
Rapid industrialization and increased geographic mobility in the nineteenth century had special implications for women because these changes tended to magnify social distinctions. As the roles of men and women played in society became more rigidly defined, so did the roles they played in the home. In the context of extreme competitiveness and dizzying social change, the household lost many of its earlier functions and the home came to serve as a haven of tranquility and order. As the size of families decreased, the roles of husband and wife became more clearly differentiated than ever before. In the middle class especially, men participated in the productive economy while women ruled the home and served as the custodians of civility and culture. The intimacy of marriage that was common in earlier periods was rent, and a gulf that at times seemed unbridgeable was created between husbands and wives.
What does the passage mainly discuss？
The main idea of the business school academic is appealing. In a world where companies must adapt to new technologies and source of competition, it is much harder than it used to be to offer good employees the job security and an opportunity to climb the corporate ladder. Yet it is also more necessary than ever for employees to invest in better skills and sparkle with bright ideas. How can firms get the most out of people if they can no longer offer them protection and promotion？
Many bosses would love to have an answer. Sumatra Ghoshal of the London Business School and Christopher Bartlett of the Harvard Business School think they have one: "employability". If managers offer the right kinds of training and guidance, and change their attitude towards their undertakings, they will be able to reassure their employees that they will always have the skills and experience to find a good job — even if it .is with a different company.
Unfortunately, they promise more than they deliver. Their thoughts on what an ideal organization should accomplish are hard to quarrel with: encourage people to be creative, make sure the gains from creativity are shared with the pains of the business that can make the most of them, keep the organization from getting stale and so forth. The real disappointment comes when they attempt to show how firms might actually create such an environment. At its nub is the notion that companies can attain the elusive goals by changing their implicit contract with individual workers, and treating them as a source of value rather than a cog in a machine.
The authors offer a few inspiring examples of companies — they include Motorola, 3M and ABB — that have managed to go some way towards creating such organizations. But they offer little useful guidance on how to go about it, and leave the biggest questions unanswered. How do you continuously train people, without diverting them from their everyday job of making the business more profitable？ How do you train people to be successful elsewhere while still encouraging them to make big commitments to your own firm？ How do you get your newly liberated employees to spend their time on ideas that create value, and not simply on those they enjoy？ Most of their answers are platitudinous; and when they are not they are unconvincing.
We can infer from the passage that in the past an employee ______.
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