Here’s the good news: our air is cleaner, our lakes are purer, our forests are healthier, endangered species are recovering, toxic emissions are down, and acid rain has diminished dramatically. And yet, if you’ve looked at a newspaper or watched the evening news lately, you might think our environment is under siege (围攻). Media Coverage of the environment is heavy on doomsday, but the truth is not at all bleak: nearly all environmental trends in the United States are positive and have been for years―if not decades. Eco-legislation, green organizations, corporate cooperation and new inventions have all quietly steered our environment in a positive direction. We can’t afford to be complacent (自满的), though―especially when it comes to greenhouse gases, since global warming is the one huge problem we haven’t really tackled. But almost every measure taken by government agencies and grass-roots efforts to improve the environment has shown encouraging results―usually faster than expected end at a lower cost. Now that’s good news. Scientists and environmentalists think that even the worrisome fact of global Warming can be ameliorated (改善). There is a strong scientific consensus that the global warming threat requires action, but if current environmental trends persist and the reduction of most pollutants continues to be accomplished faster and more cheaply than expected, we may be able to control and reduce greenhouse gases in both affordable and practical ways. Consider some of the environmental improvements the United States has witnessed over the last three decades. Take a nice, big cleansing breath. According to the Environmental Protection Agency, emissions of. the primary smog-causing chemicals from cars and trucks have declined 54 percent since 1970, even though the number of registered cars and trucks has more than doubled, from 108,407,000 to 230,428,000, and they are now driven one and a half times as far annually. Keep breathing, because the fine particulates linked to respiratory disease, including those sometimes seen as soot(煤烟), are down by about one-third since 1979 (though fewer cities were surveyed back then). The level of carbon monoxide, a dangerous odorless gas, is down 53 percent since 1970. And emissions of sulfur dioxide, often the major culprit behind acid rain, are down 49 percent since 1970, despite the fact that the United States now bums far more coal, the main source of this pollutant. These improvements have translated into better air quality for millions of Americans. Between 1976 and 1990, the Los Angeles area averaged some 150 days per year in violation of federal smog standards; in 2004, that figure dropped to just 27 violation days, the fewest ever for that city. And, in case you are wondering, federal standards have become stricter, not weaker, during this period. Of course, there is more to be done―27 smog days in Los Angeles are still 27 too many, and Atlanta, Houston and other cities continue to experience air-pollution problems. But overall, air-quality trends are strongly positive. Now, exhale. Other environmental trends are equally encouraging. Water quality has improved, too, and rates of waterborne disease are also in decline. It’s hard to believe, but just a generation ago, factories and municipal plants actually discharged untreated wastewater directly into rivers; today, though some raw sewage often makes it to waterways, almost all wastewater in the United States is treated before discharge. Even our largest metropolises have seen dramatic changes in their waterways. Remember when the filthy condition of Boston Harbor became a contentious issue in the 1988 presidential campaign Today, Boston Harbor is sparkling again. The Potomac River, which in the 1960s literally gave off a stench (恶臭), now boasts a thriving waterfront restaurant scene. And the Chicago River, a virtual open sewer in the 1960s, now hosts charming dinner cruises. Invention has always been an important force in American history. When major reductions in automobile pollution were first mandated by the Clean Air Act of 1970, automakers either called the goals impossible or claimed that cars would become ruinously expensive. Then the catalytic converter was invented. This device reduces the level of many pollutants from automobile exhaust both cheaply and reliably. Today, it is estimated that new cars and light trucks emit just 3 to 4 percent of the amount of pollution that a new car would have emitted in 1968, before regulation; soon cars emitting less than 1 percent could be seen driving around your neighborhood. Other inventions, such as an enormous device known as the electrostatic precipitator, have reduced severe emissions from power-plant smokestacks, eliminated toxic substances from manufacturing processes, and replaced CFCs. the chemicals that cause ozone-layer depletion, with other more benign compounds. And by the way, the ozone layer appears to be restoring itself. Government regulation has also been an important force in the drive to protect the environment. The mason the catalytic converter and other antipollution devices were invented in the first place is because the government required big reductions in pollution, via the Clean Air Act, Clean Water Act and other legislation. Some environmental regulation may be too cumbersome (麻烦的) and needs to be streamlined-standards can vary wildly between regions―but there isn’t any doubt that environmental regulation actually works. Individual activism has been another important factor in the amazing progress we have seen in our natural world Without the continued pressure from environmentalists, antipollution legislation would not have been enacted, and many pollution-reducing devices would not have been invented. Grass-routs organizations have been particularly essential to the ongoing creation and maintenance of new parks, wildlife refuges and protected forests. Businesses that once resisted environmental rules now generally comply. When companies started losing lawsuits regarding their chemical emissions, the idea of toxic reduction became rather popular in corporate boardrooms. But many corporations today seem to have genuinely come to believe that environmental protection is good for the country, good for the economy and, therefore, good for business. Getting a head start on the future, several big manufacturers, such as Alcoa, Boeing and Whirlpool, have already taken steps to reduce their companies’ greenhouse gas emissions. Alcoa, for example, has initiated a plan to use improved technology to reduce its greenhouse gas emissions 25 percent by 2010. The company also has extensive tree-planting programs near many of its operations and service areas, and Alcoa helps fund environmental nonprofits. Boeing and Whirlpool, meanwhile, are working to meet emissions reduction targets even though no federal law yet requires this. Business leaders, environmentalists, regulators and inventors are working toward the same goal. That’s certainly an odd mix-not clearly Republican or Democratic, nut clearly left-wing or right-wing. And maybe that’s the biggest reason you rarely hear about environmental progress. Current trends do not fit any preconceived (预想的) ideological notions. The political left wants to believe that industry is destroying the planet, and refuses to consider the evidence that business and the environment are making peace. The political right wants to believe that regulations are destroying the country, and refuses to consider the evidence that the longest period of economic expansion in American history occurred during the very period when pollution was in the midst Of its big decline. However, today’s reality―an improving environment without economic harm― does not fit with anyone’s scare-tactic fund-raising or cheap-shot political campaigns. Do the positive trends mean that environmental protection is no longer a concern Absolutely not. Many problems remain, among them the loss of wildlife habitat in suburban expansion areas, chemical runoff from nearly unrestricted agriculture, and low miles-per-gallon SUVs, which cause waste by burning excessive gas. Beyond these setbacks stands the specter (幽灵) of artificially triggered climate change. Global warming may be the Super Bowl of environmental problems, since it could impact all of Earth. But just bear this in mind: in every place where nations have imposed strict environmental standards, negative trends turned to positive very quickly. Earth, after all, has proved throughout the eons (万古) to be nothing if not resilient (能复原的) . This gives us good reason to hope that if we act to solve the environmental problems that still remain, we will achieve rapid progress against them too. Now that’s a reason to say Happy Earth Day!Which year is the fewest in violation of federal smog standards in Los Angeles A．1976B．1979C．1990D．2004