综合英语BookIII_Unit6.ppt

Unit 6 Background knowledge Nuclear Power Nuclear power can come from the fission of uranium,　plutonium or thorium or the fusion of hydrogen into helium. Today it is almost all uranium.　The fission of an atom of uranium produces 10 million times the energy produced by the combustion of an atom of carbon from coal. By 1993, there‘d been 109 licensed power reactors in the U.S. and about 400 in the world. They generate about 20 percent of the U.S.　electricity. Four types of the text Description(描述) is painting a picture in words of a person, place, object, or scene. Narration (记叙)writing includes stories , real or imaginary, biographies, histories, new items, and narrative poems. Exposition(说明) is perhaps the type of writing that is more frequently used by a student, a scientist, or a professional, exposition means expounding or explaining. Argumentation(议论) essay tries to make the reader agree with its point of view and support it, to persuade him to change his mind or behavior, and to approve a policy or a course of action that it proposes. Types of the text This is a piece of persuasive writing.　The writer deals with a controversial issue--the possibility and practicability of atomic cars. He wishes to persuade the reader to share his own reasoning and conclusion. He considers both sides of the controversy realistically. He presents known facts and bases his hypotheses on the facts.Ｔhe following shows how the two sides of the problem are put forward: 1)Building atomic cars is impracticable. a). Radiation is extremely dangerous. b). The car will have to carry many tons of lead. c). The price will be high. d). The problem of safety will remain insoluble. 2)Building atomic cars is practicable. a). It is possible to prevent radiation from escaping. b). It is possible to invent a strong but light synthetic material. c). The price will eventually go down. The writer succeeds in convincing the reader step by step, of his conclusion--it is both impossible and impr