【導(dǎo)讀】Listening. Professor. TPO2. Reading

　　

【正文】 The Chevalier states in his memoir that each night immediately after conversing with Voltaire, he wrote down everything he could remember about that particular night39。s conversation. Evidently the Chevalier kept his notes of these conversations for many years and referred to them when writing the memoir. Witnesses who lived with the Chevalier in his later life confirmed that he regularly consulted notes and journals when posing the memoir. Third, the Chevalier39。s escape from a prison in Venice. Other prisoners in that prison had even more powerful friends than he did, and none of them were ever able to bribe their way to freedom, So bribery hardly seems likely in his case. The best evidence, though, es from some old Venetian government documents. They indicate that soon after the Chevalier escaped from the prison, the ceiling of his old prison room had to be repaired. Why would they need to repair a ceiling unless he had escaped exactly as he said he did.  Reading Car manufacturers and governments have been eagerly seeking a replacement for the automobile39。s main source of power, the internalbustion engine. By far the most promising alternative source of energy for cars is the hydrogenbased fuelcell engine, which uses hydrogen to create electricity that, in turn, powers the car. Fuelcell engines have several advantages over internalbustion engines and will probably soon replace them. One of the main problems with the internalbustion engine is that it relies on petroleum, either in the form of gasoline or diesel fuel. Petroleum is a finite resource。 someday, we will run out of oil. The hydrogen needed for fuelcell engines cannot easily be depleted. Hydrogen can be derived from various plentiful sources, including natural gas and even water. The fact that fuelcell engines utilize easily available, renewable resources makes them particularly attractive. Second, hydrogenbased fuel cells are attractive because they will solve many of the world39。s pollution problems. An unavoidable byproduct of burning oil is carbon dioxide, and carbon dioxide harms the environment. On the other hand, the only byproduct of fuelcell engines is water. Third, fuelcell engines will soon be economically petitive because people will spend less money to operate a fuelcell engine than they will to operate an internalbustion engine. This is true for one simple reason: a fuelcell automobile is nearly twice as efficient in using its fuel as an automobile powered by an internalbustion engine is. In other words, the fuelcell powered car requires only half the fuel energy that the internalbustion powered car does to go the same distance. Listening Professor: The reading is correct in pointing out the problems associated with oilpowered cars. Yes, oil is a finite resource, and yes, burning oil harms the environment. However, the reading is way too optimistic in its assessment of hydrogenbased fuelcell engines. Hydrogen is not the solution to these problems. First, hydrogen is not as easily available as the passage indicates. Although it39。s present in mon substances like water, it39。s not directly useable in that form. For using a fuelcell engine, hydrogen must first be obtained in a pure liquid state. This pure liquid hydrogen is a highly artificial substance. It39。s technologically very difficult to produce and store liquid hydrogen. For example, it must be kept very very cold at minus 253 degrees Celsius. Imagine the elaborate cooling technology that39。s required for that! So hydrogen is not such a practical and easily available substance, is it? Second, using hydrogen would not solve the pollution problems associated with cars. Why? Producing pure hydrogen creates a lot of pollution. To get pure hydrogen from water or natural gas, you have to use a purification process that requires lots of energy that39。s obtained by burning coal or oil. And burning coal and oil creates lots of pollution. So although the cars would not pollute, the factories that generated the hydrogen for the cars would pollute. Third, there won39。t necessarily be any cost savings when you consider how expensive it is to manufacture the fuelcell engine. That39。s because fuelcell engines require ponents made of platinum, a very rare and expensive metal. Without the platinum ponents in the engine, the hydrogen doesn39。t undergo the chemical reaction that produces the electricity to power the automobile. All the efforts to replace platinum with a cheaper material have so far been unsuccessful.  Reading The sea otter is a small mammal that lives in waters along the western coast of North America from California to Alaska. When some sea otter populations off the Alaskan coast started rapidly declining a few years ago, it caused much concern because sea otters play an important ecological role in the coastal ecosystem. Experts started investigating the cause of the decline and quickly realized that there were two possible explanations: environmental pollution or attacks by predators. Initially, the pollution hypothesis seemed the more likely of the two. The first reason why pollution seemed the more likely cause was that there were known sources of it along the Alaskan coast, such as oil rigs and other sources of industrial chemical pollution. Water samples from the area revealed increased levels of chemicals that could decrease the otters39。 resistance to lifethreatening infections and thus could indirectly cause their deaths. Second, other sea mammals such as seals and sea lions along the Alaskan coast were also declining, indicating that whatever had endangered the otters was affecting other sea mammals as well. This fact again pointed to environmental pollution, since it usually affects the entire ecosystem rather than a single species. Only widely occurring predators, such as the orca (a large predatory whale), could have the same effect, but orcas prefer to hunt much larger