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分析企业的长期偿债能力除了关注企业资产和负债的规模与结构外，还需要关注企业的盈利能力。
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Questions 51 to 54 are based on the following passage: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 United States still have levels of carbon monoxide, particulate matter, and ozone (generated by photochemical reactions with hydrocarbons from vehicle exhaust) that exceed legally established limits. There is a growing realization that the only effective way to achieve further reductions in vehicle emissions—short of a massive shift away from the private automobile—is to replace conventional diesel fuel and gasoline with cleaner-burning fuels 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 bum 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 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 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 cost 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 clone” 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 clone” vehicles fueled with methanol they would need comparatively less fuel. Vehicles incorporating only the simplest of the engine improvements that methanol makes feasible would still contribute to an immediate lessening of urban air pollution. Which of the following most closely parallels the situation described in the first sentence of the text?（）
出生公证中，出生时间证明活动的首要依据是（）
Questions 55 to 58 are based on the following passage:For many travelers there is nothing like a big city. The big cities of a nation offer things that are usually not found in other places. Outstanding museums, plays, music, and dance groups are examples. Shops that seem to sell everything under the sun, great buildings, famous businesses, and very fine restaurants also are common.For many travelers, therefore, the city is the place to be. Yet, for some, the city has become a place to fear. They see the city as a place with too many people, too much traffic, and yes, too much crime.Here are a few suggestions and safety rules which can help the visitor to have more fun and fewer worries. Keep them in mind the next time you travel to a large city so that you can make the most of your visit.Choose a hotel which has a good reputation. Don’t choose just any place from a list of hotels and prices. Try to talk with someone who has been there.When you get to your hotel, leave any large amounts of cash and anything else of value in the hotel safe. Take them out only as you need them. It is wise not to show a lot of jewelry anyway. If you must keep things of value in your room, at least lock them in a suitcase before you go out.Keep young children with you at all times. Do not let them walk around without you.Do most of your daytime and all of your nighttime sightseeing in the city’s main areas. Go to other areas only when you are sure they are safe. You can walk safely through most big-city streets from around 8 a.m. to early evening. Never go to parks and beaches after dark or very early in the morning. At night, walk on busy, well-lighted main streets. Do not walk alone. Use a taxi when there is any question of safety or distance.Try to take a taxi owned by a major company. Be sure you can see the city number on the outside and the driver’s picture on the inside. If you are not sure of a taxi, ask your hotel doorman or bell captain. In New York City it is advisable to travel only in Yellow Cabs.If you have small children with you, give them, in writing, the name of your hotel，its phone number, and your room number. Tell them, if lost, to tell a policeman or call a telephone operator from a public place of business.Remember that there are lots of people to help you. Policemen and people in hotels, restaurants, stores, and banks can give you directions and information.Millions of people visit cities every year in perfect safety and have a great time. Follow these simple rules and you can too. This article states that（）.
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