高中英语Unit 2 Working the land知识总结 新课标 人教版 必修4

Unit 2 Working the land (知识总结)见仁见智Mark Twain once said，“Everybody complains about the weather，but nobody does anything about it.” That would later prove to be not quite right.Some people did try to do something about the weather.They tried to make it rain，or snow，and in some cases they succeeded.Dry ice，solidified carbon dioxide，was dumped from airplanes into clouds over the area that needed rain. The dry ice，and moisture from the cloud，freezes into snow and melts when it falls from the sky.One of the first times it was used successfully was in Ontario，Canada in 1948.It was called “Operation Rainmaker”. A fire was raging in Northern Ontario and people as far away as Buffalo，New York，could see the smoke.When dry ice was seeded into the clouds a rainstorm developed that helped the firemen in putting out the blaze.This method was also tried by people to make snow.Ski resort owners in the Ketchum-Sun Valley area of Idaho successfully used it.There it made snow that was badly needed for the ski runs.And what was sometimes true for rain-making was also true for snow-making.This is what happened to a hotel in Saint Moritz，Switzerland，in March of 1949.A hotel owner needed snow for his skiing guests and hired someone to make it.The hotel owner，and some of his employees，watched through binoculars（双眼望远镜）as the dry ice was being thrown out over a large area above the cloud.When the snow came down it fell north instead，at Davos，over the ski runs of a bitter rival.Another problem with rainmaking was that sometimes the clouds made too much rain. This happened one summer in Australia.C.S.Richards，a rainmaker，was blamed for causing too much rain. Everyday he received letters and telegrams blaming him for drenching（湿透）the land.Some people even accused him of dabbling（玩水）in witchcraft（魔法）.By this time，in Canada，in 1966，some people were getting fed up with rain-making; too much rain was sometimes made.One federal politician，Arnold Peters of the New Democratic Party，tried to pass a bill in the House of Commons to have the government regulate rain-making.But it failed; the government did not want to be blamed for bad weather.Written by Tony Sakalauskas现在人们越来越多地使用人工降雨来灭火、防旱、调节农作物生长、提高水库储水量等。但是人们也了解越来越多使用人工降雨的负面作用。如：破坏环境、改变气候等。【问题导入】How do you think about rain-making?A farmer: China is a big agricultural country.We depend on the weather a lot.If we can control the weather,we will benefit greatly.A citizen: I think the advantages of rainmaking outweigh（超过）its disadvantages.Successful cloud seeding means we can help plants grow,increase water levels in reservoirs（水库）,make barren（贫瘠的）soil usable and control forest fires.A environmentalist: Although cloud seeding（云的催化）is very useful,there are a lot of disadvantages.It will change local weather conditions and even cause ecocatastrophe（生态灾难）.Some countries have even used it in wars to beat enemies by creating floods.As a result, water has caused great suffering and changed local weather conditions.A student: I think rainmaking is good for agriculture.It can be used in dry areas so farmers dont have to fear a dry spell.In my opinion,it is one of the greatest inventions.Myview： 合作共赢American FarmingAt one time the United States was a nation of farmers.In 1900，about 39% of Americans or 30 million people lived on farms.A similar percentage of the labor force earned a living by working on farms.By 1990，fewer than 2% of the population lived or worked on farms.There were also fewer farms.In 1940，there were more than six million farms in America.Today there are fewer than two million. While the number of farms decreased，the size of the remaining farms increased .The average farm today is about 200 hectares.In 1900，it was 60.As the United States became an industrial nation，its farms change not only in size but in their business plans.In the past farmers raised many different crops or animals.For example，in 1900，almost all farms raised chickens.More than 75% of farms raised pigs and milk cows.In 1997，however，only about 6% of farms raise these animals.The trend in American farming has been to specialize.Farmers put their efforts into intensively raising only a few things.New technology has helped create specialized systems that produce more using less labor.Two examples of this are milk and corn. Since 1924，American milk production has grown almost 100%，but the number of milk cows has decreased by half.Cows today produce more than four times more milk than their ancestors 80 years ago.The same is true for corn. Improved kinds of corn produce about 4.7 times more corn per hectare than 100 years ago.Economists call producing more with less an increase in productivity.The Department of Agriculture uses a measure called an index to show how productivity changes.It says Americas agricultural productivity increased by more than 100% between 1950 and 1996.Over the same period，prices of the agricultural goods fell by more than 50%.So the trend toward increased productivity had meant lower prices.Many farmers have answered by increasing the size of their specialized operations.Information in this report comes from the National Agriculture Statistics service.【任务导入】 Make a comparison between Chinese farming and American farming.Divide the members into two groups，one group focuses on Chinese farming，the other one focuses on American farming.Make a competition and show which group do better.Then work together to write a research report on Comparison Between Chinese Farming And American Farming and ask some experts to check it or get some advice to perfect it.读书做人【话题链接】Jia Sixie and His Qi Min Yao ShuJia Sixie，who was born in Yidu district（now Qingzhou）in Shandong Province，was an agriculturist（农学家），of the Northern Wei Dynasty（386-534 AD）.He once worked as the