高中英语 Unit3 protecting ourselvesgrammar and usage精品教案 牛津译林版选修10.doc

unit 3 protecting ourselvesgrammar and usagestep 1 general introductionthe grammar items in this unit focus on one aspect of the structure of a textthe development of a text. you will learn how a text should be written to allow readers to move from one idea to the next easily. you will get to know that there are four features that can help develop a text logically. you are expected to apply what you have learnt to practice by finishing an exercise.step 2 explanationthe development of a text1. turn your books to pages 34 and 35 and have a look: t: how many paragraphs are there in the text? (there are ten paragraphs.) t: what is the title of the text? (the title is aids today.) t: can we learn what the text is about from the title? (yes. we learn that the text is about the deadly disease of aids at the present time.) t: if you are asked to divide the whole text into several parts, how will you divide it?(we can divide it into three parts. the first part is the introduction in the first paragraph. the second part is the main body and includes the next eight paragraphs. the conclusion is the last paragraph, and is the last part.) t: what is the main idea of the first part? (it gives us an example to show us how serious the situation of aids is in africa.) t: what is the second part about? (it tells us some detailed information abut aids. for example, what causes aids, the ways people get infected with aids, how serious the situation is around the world and what the un and the chinese government have been doing to deal with this situation.) t: what is the last part about? (it refers again to the example mentioned in the first paragraph and points out the key to stopping aids in the future.) t: now we can see how a text is developed. we know that a text usually includes several parts. we call these parts the title, the beginning paragraph, the body paragraphs and the concluding paragraph. now, lets go over the grammar and usage section to learn how to develop a text logically.2. read the guidelines and part 1. can you also think of some titles of some other articles that are not too long and are clear and simple? 3. go over the three points of part 2 and see what should be included in the beginning paragraph.4. go over part 3. this part will tell you that each body paragraph usually contains a topic sentences and a concluding sentence to the paragraph. try to find what the topic sentence should be like and where it can be found, what supporting sentences are, and what the function of a concluding sentence is in a paragraph.5. read part 4 and try to find how the concluding paragraph functions in a text. 6. do the exercise on page 41. read the sentences and decide which paragraph they belong to and what type of sentence each one is. answers:beginning paragraphtopic sentencesupporting sentencehookbody paragraph 1topic sentencesupporting sentencebody paragraph 2topic sentencesupporting sentenceconcluding paragraphtitleconcluding sentencefidgeachbstep 3. practice1. now lets come to parts c1 and c2 on page 116 in workbook, so that you can have more chances to practice what you have learnt in this section.2. read the following passage and do the exercises as you are required to.are there extra-terrestrials? (1) many scientists today believe that life exists elsewhere in the universelife probably much like that on our own planet. they reason in the following way. (2) as far as astronomers can determine, the entire universe is built of the same matter. they have no reason to doubt that matter obeys the same laws in every part of the universe. therefore, it is reasonable to guess that other stars, with their own planets, were born in same way as our own solar system. what we know of life on earth suggests that life will arise wherever the proper conditions exist. (3) life requires the right amount and kind of atmosphere. this eliminates all those planets in the universe that are not about the same size and weight as the earth. a smaller planet would lose its atmosphere; a larger one would hold too much of it. (4) life also requires a steady supply of heat and light. this eliminates double stars, or stars that burn up suddenly. only single stars that are steady sources of heat and light like our sun would quality. finally, life could develop only if the planet is just the right distance from its sun. with a weaker sun than our own, the planet would have to be closer to it. with a stronger sun, it would have to be farther away. (5) if we suppose that every star in the universe has a family of planets, then how many planets might support life? first, eliminate those stars that are not like our sun. next, eliminate most of their planets; they are either too far from or too close to their suns. then eliminate all those planets which are not the same size and weight as the earth. finally, remember that the proper conditions do not necessarily mean that life actually does exist on a planet. it may not have begun yet, or it may have already died out. (6) this process of eliminate seems to leave very few planets on which earthlike life might be found. however, even if life could exist on only one planet in a million, there are so many billions of planets that this would still leave a vast number on which life could exist. the title _ the beginning paragraph _ topic sentence _body paragraph 1 _topic sentence _body paragraph 2 _topic sentence _body paragraph 3 _topic sentence _body paragraph 4 _ the concluding paragraph _ topic sentence _answers:the title: are there extra-terrestrials?the beginning paragraph: paragraph 1topic sentence: many scientists today believe that life exists elsewhere in the universelife probably much like that on our own planet.body paragraph 1: paragra