听力原文：Listen to part of a lecture in a computer science class. Professor All right, why dont we get started here...how many of you own and can operate a computer? ... Two, four, six..., lets see...nineteen; hmm, thats quite a few of you. OK, well, we all know how popular...no, not just popular...how necessary business and family computers are becoming and how much a part of modern-day life they are now; and so today, I am going to talk about computers. But actually, I dont intend to talk about the function and operation of computers, but about a problem that is both worrying and very dangerous: computer crime. Lets look more closely at this modern crime. One thing is certain; Computers and especially computer networks have created opportunities for crime that never existed before, and as a result, the police and justice departments are becoming increasingly concerned about the growing number of computer users who are gaining access to private or secret information. Its a problem that is on the rise worldwide. Statistics are showing a trend toward more computer crimes every year. As we all know, the information that passes through computer networks can be sensitive and dangerous if the wrong people get access to it. War Games, a 1980s movie, illustrates this point very well. In War Games, a young, high school boy gains access to the United States computerized military defense system with the intention of playing a game, but ends up nearly starting a nuclear war. This theme is, of course, exaggerated...it is very unlikely that any one, much less a high school boy, could penetrate the U. S. military security system, which limits access to extremely sensitive networks within the government. But the idea behind the movie is a disturbing one. People can and, in fact, are using their experience in operating computers to break into networks... and are causing a lot of inconveniences and, even worse, are committing crimes and exposing others to danger. The point is this: Computer crime is very real and dangerous. Computer crime is tempting for two reasons: number one, some computer geniuses have trouble resisting the challenge. They just want to see if they can do it. And number two, computer crime sometimes has some very significant rewards. Now get ready to answer the questions. You may use your notes to help you answer. 23. What is the talk mainly about? Listen again to part of the lecture. Then answer the question. Professor All right, why dont we get started here...how many of you own and can operate a computer? ... Two, four, six... lets see... nineteen; hmm, thats quite a few of you. OK, well, we all know how popular...no, not just popular...how necessary business and family computers are becoming and how much a part of modern-day life they are now.... 24. Why does the professor say this? Professor All right, why dont we get started here...how many of you own and can operate a computer? 25. What has created opportunities for computer crimes? 26. What kinds of computer users are police becoming increasingly concerned about? 27. Why does the professor mention the movie War Games? 28. According to the talk, what can NOT be concluded?Narrator Listen to part of a lecture in a computer science class. Now get ready to answer the questions. You may use your notes to help you answer. What is the talk mainly about?