题目

(9分)从某一高度处水平抛出一物体，它着地时速度是50m／s，方向与水平方向成。（取g＝10m／s２，，）。求：(1)抛出点的高度和水平射程；(2)抛出后3s末的速度。 答案：（1）设着地时的竖直方向速度为，水平速度为则有（1分）（1分）抛出点的高度为         （1分）水平射程   （2分）（2）抛出后3s末的速度为，则有         （2分）解得        （2分）The economic growth that many nations in Asia and increasingly Africa have experienced over the past couple of decades has transformed hundreds of millions of lives – almost entirely for the better. But there’s a byproduct to that growth, one that’s evident – or sometimes less than evident – in the smoggy, smelly skies above cities like Beijing, New Delhi and Jakarta. Thanks to new cars and power plants, air pollution is bad and getting worse in much of the world, and it’s taking a major toll (伤亡人数，代价) on global health.How big? According to a new analysis published in the Lancet, more than 3.2 million people suffered deaths from air pollution in 2010, the largest number on record. That’s up from 800,000 in 2000. And it’s a regional problem: 65% of those deaths occurred in Asia, where the air is choked by diesel soot (内燃发动机烟雾) from cars and trucks, as well as the song from power plants and the dust from endless urban construction. In East Asia and China, 1.2 million people died, as well as another 712,000 in South Asia, including India. For the first time ever, air pollution is on the world’s top – 10 list of killers, and it’s moving up the ranks faster than any other factor.So how can air pollution be so damaging? It is the very finest soot – so small that it roots deep within the lungs and then enters the bloodstream – that contributes to most of the public – health toll of air pollution including death. Diesel soot, which can also cause cancer, is a major problem because it is concentrated in cities along transportation zones affecting overpopulated areas. It is thought to contribute to half the deaths from air pollution in urban centers. Fro example, 1 in 6 people in the U.S. live near a diesel – pollution hot spot like a rail yard, port terminal or freeway.We also know that air pollution may be linked to other non – deadly diseases. Fortunately in the U.S. and other developed nations, urban air is for the most part cleaner than it was 30 or 40 years ago, thanks to regulations and new technologies like the catalytic converters (催化式排气净化器) that reduce automobile emissions. Govemments are also pushing to make air cleaner – see the White House’s move last week to further tighten soot standards. It’s not perfect, but we’ve had much more success dealing with air pollution than climate change. Will developing nations like India eventually catch up? Hopefully – though the problem may get worse before it gets better. The good news is that it doesn’t take a major technological advance to improve urban air. Switching from diesel fuel to unleaded (无铅燃油) helps, as do newer and cleaner cars which are less likely to send out pollutants. Power plants – even ones that burn mineral fuels like coal – can be fitted with pollution – control equipment that, at a price, will greatly reduce smog and other pollutants.But the best solutions may involve urban design. In the Guardian, John Vidal notes that Delhi now has 200 cars per 1,000 people, far more than much richer Asian cities like Hong Kong and Singapore. Developing cities will almost certainly see an increase in car ownership as residents become wealthier – and that doesn’t have to mean deadly air pollution. Higher incomes should also lead to tougher environmental regulations, which is exactly what happened in the West. We can only hope it happens before the death toll from bad air gets even higher. 小题1:What tends to give rise to the highest death toll according to the passage?A．The lack of tight environmental protection standards.B．The increasing numbers of the diesel cars and trucks.C．The frighteningly high death rate from deadly cancer.D．The world’s serious air pollution such as soot and dust.小题2:The “byproduct” (Paragraph 1) most probably refers to     .A．consequenceB．solutionC．reformD．design小题3:The basic reason why so many people die from air pollution is that       .A．the diesel soot is too small to be seenB．the diesel soot is much too poisonous to breatheC．the diesel soot roots in lungs and gets into bloodD．the diesel soot can also contribute to deadly cancer小题4:According to the passage, the writer actually wants to convince the readers that        .A．the global economic growth is mainly to blame for air pollution and climate changeB．the developing countries are repeating the same mistakes as the developed ones madeC．the ecological situation and air pollution in India are becoming worse and worseD．the unbeatable air is increasingly becoming a major killer throughout the world小题5:By describing urban design as “the best solution” in the last paragraph, the writer means that        .A．the making of tougher environmental regulations alone is of little useB．more sever regulations should be made to handle air pollutionC．the urban construction in western developed countries is the best choiceD．the pace of development has to be slowed down to reduce air pollution