【名校课件】人教版必修4：Unit2Workingtheland（usinglanguage）.ppt

Chemical Or Organic Farming?; green food;Chemical Or Organic Farming?;First reading: get the main idea of each paragraph. para1: A new discovery of scientists. para2: Several problems caused by using chemical fertilizers. para3: The advantages of using organic farming. para4: Some methods to keep the soil fertile.;1 Why are chemical fertilizers so popular in farming today? 2 After the long-term use of chemical fertilizers, what have scientists found?;;Read paragraph 3-4;; 1 …such as wheat or corn that need rich and fertile soil. 2 …planting peanuts that use the ground’s surface followed by vegetables that put down deep roots.;para1: A new discovery of scientists. para2: Several problems caused by using chemical fertilizers. para3: The advantages of using organic farming. para4: Some methods to keep the soil fertile.; 请以“PLASTIC OR CLOTH BAGS?”为题模仿这篇文章的篇章结构和句子结构去写一篇说明文。 ;Discussion and practice;The following words may help you.;Homework : Finish the writing .;Over the past half century, …have become very common …. …welcomed them as a … way to …. Recently, however, we have been finding that they can cause damage to …, even …, to people’s health. What are some of the problems caused by …? First,… With these discoveries, …are beginning to turn to …. ….;Para1 Topic Para2 Problems Para3 Advantages Para4 Several methods ; Over the past half century, plastic bags have become very common in our daily life. We welcomed them as a convenient way to carry goods. Recently, however, we have been finding that they can cause damage to the environment, even worse, to people’s health.; What are some of the problems caused by plastic bags? First, people often leave plastic bags here and there, making white pollution. Second, it takes a long time, more than 100 years ,to be exact, to break up .Last but not least, when heated, plastic bags can produce something harmful, which can build up in our body and eventually lead to cancer or other illnesses.; With these disc