Unit 6 FREE TIME AT HOME（课件）-2018年英语同步优化指导（教科版必修2）

Unit 6　FREE TIME AT HOME 英语　必修2(E) 电视始于19世纪末，流行于20世纪50年代。电视有着好的方面和不好的方面，但它给人们带来了快乐和乐趣，改变了我们的生活和社会。 英语　必修2(E) Television is an electronic system for transmitting still or moving images(usually with sound)to receivers that project a view of the images on a picture tube or screen.Experimentation to create a workable television system began in the late 19th century.In 1884 Paul Nipkow，a German scientist，patented his ideas for a complete television system.In 1926 in England，John L．Baird，first demonstrated a true television system by electrically transmitting moving pictures.By the early 1950s a colour­ television system had been developed. 英语　必修2(E) Since the 1950s the improvements in colour­television technology have resulted in larger picture tubes with clearer images.In addition，a device for projecting television onto a large screen became available in the late 1970s.In the late 1990s digital television came into being. Television became common in the early 1950s.Since then，millions of children have grown up in front of the set.Many people now worry about the effect of TV on the young.They wonder if television should be allowed to go on.Many parents wish that there had never been such an invention.Why are they so afraid？Is television really harmful? 英语　必修2(E) Like almost anything else，television has its good sides as well as its bad sides.It has brought joy and interest into the lives of the old，the sick and the lonely.Without it some of these people would have little pleasure in the world. Unfortunately，some television programmes have been very harmful to the young.Children do not have enough experience.They do not know that TV programmes often show an unreal world.Commercials tell lies in order to sell products that are sometimes bad or useless.Children believe them and want to imitate what they see on TV. 英语　必修2(E) They believe that the murders on TV screens are normal and acceptable.By the time they are out of high school，more young people have watche