Unit5 课文译文及知识点总结课件【知识建构+精讲精练】高中英语人教版（2019）选择性必修第一册

Chemical Versus Organic FarmingEvaluate chemical farming and organic farming1Read the Passage Chemical pesticides and artificial fertilisers have been in widespread use in farming since the middle of the 20th century.When they were first introduced,many farmers welcomed them as a great way to fight crop disease and increase production.Over time,however,what some scientists have found is that their long-term use can sometimes harm both the land and peoples health.Chemical Versus Organic FarmingMark where it needs a pause.For example,pesticides can damage the land by killing not only harmful bacteria and insects,but also helpful ones.In addition,these chemicals can stay in the soil and underground water sources for a long time.This affects the crops grown on the land and,in turn,the animals and humans who digest them.Many people worry that these chemicals may make them ill and even cause cancer.In fact,some pesticides like DDT have been prohibited in most countries because of the damage they cause to people and the environment.As for chemical fertilisers,crops grown with them usually grow too fast to be rich in nutrition.They may look beautiful on the outside,but inside there is usually more water than essential minerals,and they often have less flavour as well.As an alternative,some farmers have switched to organic farming,and many customers have turned to organic food when they shop at the local grocery.Organic farming is simply farming without using any chemicals.Organic farmers focus on keeping their soil rich and free of disease through natural means.For example,many organic farmers use natural waste from animals as fertiliser.This makes the soil in their fields richer in minerals.It also keeps the air,soil,water,and crops free of chemicals.Organic farmers also use many other methods to produce rich soil.They often change the kind of crop grown in each field every year.For instance,they may grow corn or wheat in a field one year,and then grow beans there the next.Why different crops are grown is because they put important minerals back into the ground,making it ready for the next batch of crops.Organic farmers also plant diverse crops that used different depths of soil to help keep it rich.For example,peanuts grow on the grounds surface,but many other vegetables put down deep roots.The goal of using different organic farming methods is to grow good food while avoiding damage to the environment or to peoples health.Some people would prefer to stop the use of man-made chemicals in agriculture entirely.What keeps them from doing so is the fact that chemical farming serves the high demand for food around the world.Organic farming is nowhere near able to meet that need.Therefore,there is still a long way to find a suitable solution that puts sufficient food on the dinner table while keeping people and the environment as healthy as possible.2课文知识点讲解Chemical Versus Organic Farming化学耕作化学耕作与与有机耕作有机耕作versus:used to compare two different ideas,choices,etc.（比较两种不同想法、选择等）与相对，与相比 Para1 Chemical pesticides and artificial fertilisers have been in widespread use in farming since the middle of the 20th century.When they were first introduced,many farmers welcomed them as a great way to fight crop disease and increase production.Over time,however,what some scientists have found is that their long-term use can sometimes harm both the land and peoples health.1.pesticide：pest害虫+i+cide=killcut“切开，杀”2.in widespread use 在广泛使用中3.introduce:推行；实施；采用4.fight crop disease 抵制作物病害 to fight crop disease and increase production 不定式作a great way 的后置定语5.over time 随着时间的流逝5.what some scientists have found是what 引导的主语从句Para2 For example,pesticides can damage the land by killing not only harmful bacteria and insects,but also helpful ones.In addition,these chemicals can stay in the soil and underground water sources for a long time.This affects the crops grown on the land and,in turn,the animals and humans who digest them.Many people worry that these chemicals may make them ill and even cause cancer.In fact,some pesticides like DDT have been prohibited in most countries because of the damage they cause to people and the environment.As for chemical fertilisers,crops grown with them usually grow too fast to be rich in nutrition.They may look beautiful on the outside,but inside there is usually more water than essential minerals,and they often have less flavour as well.1.bacteria n(单数bacterium）细菌2.in turn 相应地；转而；依次3.digest vt vi 消化；vt 领会；领悟4.as for 至于。as for 常位于句首，用以转换话题。5.too-to-太而不能6.essential:(to/for sth)(to do sth)(that.)SYN vital完全必要的；极其重要的1in turn相应地；转而；依次；轮流This in turn attracts more users and advertisers,and so on.这反过来又吸引了更多的用户和广告商等。We will examine each of these methods in turn.我们将依次逐个分析这些方法。知识总结(1)take turns to do/in doing sth.轮流做某事Its ones turn to do sth.轮到某人做某事了by turns轮流地，交替地(2)in return作为回报in return for作为对的回报归纳总结单句语法填空The children called out their names _ turn.Its my turn _(clean)the classroom.Theory is based on practice and _ turn serve