2008年12月大学英语四级预测试题及答案解析.docVIP

2008年12月大学英语四级预测试题及答案解析 一、阅读理解第1题： Electric cars are dirty. In fact, not only are they dirty, they might even be more dirty than their gasoline-powered cousins. 　　People in California love to talk about “zero-emissions vehicles,” but people in California seem to be clueless about where electricity comes from. Power plants most all use fire to make it. Aside from the few folks who have their roofs covered with solar cells, we get our electricity from generators. Generators are fueled by something — usually coal, oil, but also by heat generated in nuclear power plants. There are a few wind farms and geothermal plants as well, but by far we get electricity mainly by burning something. 　　In other words, those “zero-emissions” cars are likely coal-burning cars. Its just the coal is burned somewhere else so it looks clean. It is not. It’s as if the California Greens are covering their eyes — “If I can’t see it, it’s not happening.” Gasoline is an incredibly efficient way to power a vehicle; a gallon of gas has a lot of energy in it. But when you take that gas (or another fuel) and first use it to make electricity, you waste a nice part of that energy, mostly in the form of wasted heat — at the generator, through the transmission lines, etc. 　　A gallon of gas may propel your car 25 miles. But the electricity you get from that gallon of gas wont get you nearly as far — so electric cars burn more fuel than gas-powered ones. If our electricity came mostly from nukes, or geothermal, or hydro, or solar, or wind, then an electric car truly would be clean. But for political, technical, and economic reasons, we don’t use much of those energy sources. 　　In addition, electric cars’ batteries which are poisonous for a long time will eventually end up in a landfill. And finally, when cars are the polluters, the pollution is spread across all the roads. When it’s a power plant, though, all the junk is in one place. Nature is very good at cleaning up when things are not too concentr