1、19-A. Animals at Risk: Who Cares?An animal species becomes extinct when it fails to produce enough young in each generation to keep pace with the death-rate. We can tell from fossil evidence inrocks that many living species have become extinct over the millions of years since life began. It is a nat
2、ural process and extinction is the fate of any animal that has specialized too far to change when its environment changes, or has to compete with a better-adapted and more powerful animal. Because of remarkable technical developments during the past few centuries, man has destroyed or nearly destroy
3、ed some species by killing them at such a rate that they couldnt produce enough offspring, or by completely changing their natural environment at surprising speed.A number of examples can be given of the way in which natural environments are being rapidly changed - Amazonia, for instance. There is e
4、very likelihood that many species of animals will be made extinct because of these and similar clearances of natural vegetation. Large numbers of animals have been hunted and killed for food. The North American buffalo is a case of the near-extinction of a species through hunting. Often the numbers
5、are so great the hunters may not realize the danger. But even when the danger is widely publicized, the financialrewards for the hunters may be so great that they choose to ignore the threat tothe species. Attitudes like this have led to hunters killing animals for furs, for ivory or merely for orna
6、ments. A slight variation on this is when tourists hunt animals for trophies. Magnificent creatures such as lions and tigers have been hunted out of existence in some parts of the world. It is important to realise, though, that animals are sometimes killed out of fear. Big cats are killed in this wa
7、y. And animals are sometimes killed out of a wish to reduce numbers to help the species to survive. The killing of the Canadian seals is claimed to be for this purpose, and the use of their skins for furs is only a by-product.Many people are concerned about animals and wildlife conservation. One way
8、 to preserve species under threat of extinction - whatever the cause - is to remove them to zoos and parks and breed them there. There is always the chance that enough offspring will be born to return them one day to their natural environment - provided it still exists, and that hunters dont kill th
9、em again! Another method is to protect the animals in their natural environment by creating wildlife reserves and parks and using game wardens to look after them. But the parks are large, the wardens few and the determination of hunters very great. Early in 1980 wardens and hunters clashed in East A
10、frica. The hunters were armed with modern weapons and several people were killed.There is great pleasure in watching wildlife in natural or near-natural environments, and tourism can add to the income of countries. The animals are still resources - but in a very different form.Unit 19 Text A动物处境危险：谁
11、来关心一种动物，如果不能在每一代都生育出足够的后代以便与死亡率保持同步，它就开始灭绝。根据岩石中找到的化石证据，我们可以说，自有生命以来的千百万年中，许多物种已经灭绝。这是一个自然的过程，一种动物如果过分特化，不能随环境的变化而改变，或者不得不与比它更有适应性，更强大的动物进行竞争，那么这种动物注定要灭绝。由于近几个世纪以来技术的巨大发展，人类大量捕杀动物，使它们无法繁殖足够的后代，或者以惊人的速度彻 改变动物生 的自然环境， 而 灭 或几 灭 一 物种。我们可以 出许多自然环境 在 速改变的 ， 就是一个 。由于自然 物在这 或类 的 ，许多动物物种 有可能灭绝。大量动物 杀 。curren
12、cy1便是捕 而“灭绝物种的一个 。动物量如fifl大，以 捕 者可能不到它们 在灭绝的危险，使人们 这种危险，捕 者”经如fi巨大，无 物种灭绝的危险。这种度已使捕 者 得，或 得一 而捕 动物。与fi 有不同的是，者们 杀动物是 纪。有 大动物， 如 ，在世 一 已 杀 。 要 的是，人们有 出于 而 杀 动物。许多大 动物fi 杀 的。有 人们捕杀动物是 它们的量，使 物种得以生 。捕杀 大 据 就是出自这一 的，而 是 。许多人 分关心动物 生生物的保 。保 “灭绝的物种，不 是 么， 法fl一是这 物种 到动物 ，在那。以后如果动物生 的环境 在，而 人类不 捕杀它们，我们 有可能它
13、们的后代繁殖到足够量以便有朝一日 它们放归自然！另一种 法是建立 生动物禁 区 生动物 雇 人员照看它们，以fi保 动物在自然环境生活。是 生动物 范围很大，看守人员较 ，而捕 者的决心却很大。1980年初看守人员与捕 者曾在东非发生冲突。捕 者配有现代化武器，有人 杀。在自然的或接近自然的环境观看 生动物是一种很大的乐趣，这样的业能给 增收入。动物是资源不过是一种形式上 分不同的资源。19-B. The Killer SmogsOn the night of December 1, 1930, a dense fog moved over the Meuse Valley, in Belgi
14、um. Many factories in the valley poured smoke and fumes into the foggy air.This created a dark smog of smoke and fog combined. People in the valley began to cough and strain for breath. The smog remained for four days. During that time, thou-sands of people became ill. The hospitals were filled with
15、 patients. Sixty people died. Most of them were older persons with heart and lung problems.Finally, a heavy rain washed away the smog. Scientists studied the causes of thedisaster. They concluded that the illnesses and deaths were caused by chemicals in the smog.The first reported event of this kind
16、 in the United States happened in Donora, afactory town in a valley near Pittsburgh. In 1948, a killer smog made half of the population sick, there were 17 deaths. Again, older people with lung or heart diseases were hit hardest.London, England, has always been known for its “black fags.“ In the win
17、ter of 1952, a milky white fog rolled into the city. It soon turned into black smog as the smoke of the city poured into the air. It was so hard to see that people hadto walk in front of the buses to guide them. In this way, the most serious air pollution disaster in history began. When it was over,
18、 more than 4,000 people had been killed by the thick black smog.New York City has had several London-type smogs since 1950. Each time, there were from 100 to 400 deaths caused by the smog. Although these smogs were not asdeadly as Londons, New York City has the worst: air pollution problem in the Un
19、ited States.In all the killer smogs, factories and homes poured smoke and fumes into the airfrom the furnaces. The chemical fumes combined witty the water droplets in the fog to form harmful substances. These substances caused the illness of those whobreathed the polluted air.Usually, such harmful f
20、umes rise into the upper air and are blown away by the wind. Hut sometimes there is an unusual weather condition called a temperature inversion. A layer of cold air remains near the ground as smoke and fumes pour into it. This is covered by an upper layer of warm air that acts like a lid. It prevent
21、s the polluted cooler air from rising. The harmful fumes pile up and makepeople ill. The smog may bc so thick that airports are closed and chains of collisions occur on the highways.Another type of smog occurs in Los Angeles. Here the weather may he clear and sunny. But stinging eyes and dry coughs
22、show that harmful chemicals fill the air. The smog is due to invisible gases, mostly from automobile exhaust. Becausethese chemicals are changed by the sun high up in the air, Los Angeles smog is called photochemical smog. It contains automobile exhaust fumes and nitrogen oxides changed by the suns
23、rays. Added to these are sulfur dioxide and other fumes from factories and oil refineries. Photochemical smog is found in many large cities all over the world.Killer smogs dont happen very often, fortunately. Hut in many large cities, a combination of automobile exhaust fumes, home furnace smoke, an
24、d factory waste gases pours into the air. This may also happen in the suburbs, or out in the country, where large factories have been built. A number of harmful substances have been found in the air there. When these substances are breathed in day after day, the health of the population is affected.
25、Unit 19 Text B 人死命的烟雾1930年12月1日晚，浓雾笼罩着比 默兹河流域。默兹河流域的许多工厂烟尘排入雾气蒙蒙的空中，这样形成 烟与雾的混合物：黑色的烟雾。当 的居民开始咳嗽，呼吸困难。烟雾持续 四天，在fi期间，有几千人得病。医院住满 病人。60人死亡。他们中多是患有心肺疾病的 年人。最后，一场大雨烟雾荡涤干净。 学 研究 这场灾难的 ，他们得出的结说，疾病死亡者是烟雾中的化学物质造成的。 首次报告的这类事件发生在多诺拉，匹兹堡附近的一个工业小镇。1948年 人死命的烟雾使一半居民得病，有17人死亡。同样，患有肺病或心脏病的 年人受 最严 。的 以 黑雾 。1952年 天，
26、一 色的浓雾 入这个 。随着 的烟排入天空，雾很 变成 黑色烟雾。看东 如fi困难，以 人们不得不 在 。 上最严 的空气 灾难就这样开始 。当这场灾难结 ，有4000多人死于浓黑烟雾。自1950年以来。 发生过几次 式的烟雾。每次烟雾都造成100到400人死亡。然这 烟雾不烟雾那么 命， 的空气 在 是最严 的。在种 人死命的烟雾中都有工厂 currency1排放到空气中的烟尘。化学烟尘与雾气中的结合在一“形成有 物质。这 物质使呼吸到 空气的人得病。这种有 烟尘”上到空气的上， fifl 。有 出现一种的天气， 度增。有一空气在接近 的 ，当烟尘排入空气中。上 的”空气罩着它们， 就一个
27、。上”空气使得 的空气无法上。这样，有 烟尘便 “来，使人得病。烟雾有可能如fifl浓，以 场关， 上续发生 事。在出现 另一类烟雾。那天气 ， 。是人们 干咳，说 空气 满 有 的化学物质。这种气 烟雾是由一 看不 的气 造成的，中大 分是 气。这 化学物质”受到空中的照 而发生变化， 以烟雾 化烟雾。这种烟雾 有 排放的 气 照 后发生变化的 化 。 fifl ， 有来自工厂 厂的 化它烟尘。 世 许多大 都有化烟雾。人死命的烟雾不出现。在许多大 ， 气， currency1烟尘以 工厂 气的混合物排放到空气中。这种 可能出现在建有大工厂的区 的 。那 的空气中已发现一 有 物质。人们日 一日 呼吸这 有 物质， 便”受到 。
