人教版高中英语必修4第二单元-Using-LanguageⅡ(共36张PPT)-(1).ppt

Now, which one do you prefer? A B a product of chemical farming a product of organic farming green food organic food 1.Do you know what is organic farming? 2.Which kind of fertilizer do farmers use when they are doing organic farming, chemical fertilizers or natural fertilizers ? Pre-reading Chemical Or Organic Farming? Reading 1. Scan the passage and get the main idea of it. The ____________ between _________ farming and __________ farming. comparison chemical organic 2. Find out and underline the topic sentence of each paragraph. Recently, however, scientists have been finding that long-term use of the chemical fertilizers can cause damage to the land and, even more dangerous, to people’s health. What are some of the problems caused by chemical fertilizers? Find out and underline the topic sentence of each paragraph. Para1. Para2. Skimming Para 3. Para 4. With these discoveries, some farmers and many customers are beginning to turn to organic farming. Organic farmers also use many other methods to keep the soil fertile. Second reading ( 5ms ) Read the text again and answer the following questions: 1 Why are chemical fertilizers so popular in farming today? 2 What problems can be caused by using chemical fertilizers ? 3 What is organic farming ? 4 What is the main reason for using organic farming methods ? 1.Why are chemical fertilizers so popular in farming today ? They can stop crop disease and increase production. 2 What problems can be caused by chemical fertilizers ? There are three problems. First, chemical fertilizers affect the soil and the water supply badly. Second, they allow farmers to grow the same crop year after year and exhaust the soil. Third, they kill both helpful and harmful pests. Organic farming is simply farming without using any chemicals . 3 What is organic farming ? 4 . What is the main reason for using organic farming methods ? A healthy soil reduces disease and hel