结构推理 Directions: Read the following passage carefully and give brief answers to the questions. The increase in the price of oil has brought the world to its senses. Scientists are searching for a suitable alternative, but so far without success. They are considering how they can make better use of the two other major fuels, coal and natural gas, but they have found that neither can take the place of oil in their economy. In recent years there has been a growing concern for the environment and coal is not a popular fuel with environmentalists (环境保护论者). Natural gas, the purest of the three fuels, is also the most limited in supply. The answer would seem to lie in nuclear power stations. They need very little fuel to produce enormous amounts of power and they do not pollute the atmosphere (空气). Their dangers, however, are great and the costs of building them are also high. Scientists have recently turned their attention to natural sources of energy: the sun, the sea, the wind and hot springs. Of these the sun seems the most promising source for the future. Houses have already been built which are heated entirely by the sun. However, energy from the sun can only be collected during daylight hours, and in countries where the weather is rainy, an alternative heating method has to be includeD、However, many scientists are sure that new ways of generating large amounts of energy will be successfully developed, but at the same time they fear the results. If the world population goes on increasing at its present rate, we may, in fifty years’ time, be burning up so much energy that we would damage the earth’s atmosphere. By raising the temperature of the atmosphere, we could change the pattern of vegetable and animal life throughout the world — a frightening possibility. 1. What are the three major sources of energy at present? 2. Why does the answer to the problem of fuel shortage seem to lie in nuclear power stations? 3. What are the weak points of nuclear power stations? 4. What natural sources of energy have scientists recently turned their attention to? 5.What results do many scientists still fear?