题目

如图是甲、乙两物质在高温条件下发生化学反应的微观示意图，根据图示回答： （1）该反应的基本类型是            ；上述反应中，不发生改变的粒子是   （填“分子”或“原子”） （2）上述反应的化学方程式是                                              。 答案：（1）置换反应                原子  （2）                                           C                  Genetically modified (GM) foods (转基因食品) have been around for many years. They are developed for a number of different reasons — to fight disease,resist pests,improve nutrition,survive drought — and are mainly found in our food supply in processed foods using com,soybeans and as feed for farm animals. Are they safe? How do they affect the environment? Can they improve food security? Is the world better off with or without GM foods?                 Supporters of GM foods say that farmers who grow these crops are able to use fewer environmentally damaging farm chemicals. The increased output is important to feeding the world's growing population. And many studies have shown that GM foods are safe to eat and that there's no actual evidence of any health risks. They also add that the oods have been thoroughly examined and have gamed approval for eating from a wide variety of government and scientific bodies.                 Critics,however,are concerned that these foods have not been strictly tested and are potentially dangerous for both the environment and people's health. They say farmers growing GM crops have actually increased their use of farm chemicals. And the widespread use of the crops,they say,has also led to an increase in weeds and insects that have resistance to farm chemicals. And,they argue,there is still no scientific evidence of the long-term safety of these foods.                 Four scientists recently took on those questions in a debate,facing off two against two on GM foods. In these Oxford-style debates,the team that gets the most people on its side by the end is the winner.                 Before the debate,the audience at the Kaufman Music Center in New York voted 32 percent in favor of GM foods,with 30 percent against and 38 percent undecided. Afterward,60  percent agreed with GM foods,and 31 percent disagreed — making the side arguing in favor of GM foods the winners of this debate.29. What's the main purpose of Paragraph 1 ?   A. To advertise GM foods.   B. To show what GM foods are.   C. To introduqe the topic of the text.   D. To explain why GM foods are developed.30. What's the main focus of the debate?   A. The necessity of producing GM foods.   B. Whether GM crops can help to avoid hunger.   C. Whether GM. foods are scientifically examined.   D. GM foods’ effect on human health and the environment.31. What do we know about the debate at the Kaufman Music Center?   A. There were four votes for the debate.   B. About half of the audience had no idea about it.   C. It was a face-to-face debate between two and two.   D. The winner of the debate was decided by the judges.32. What percentage of the audience supported the winner of the debate?   A. 31 percent. B. 38 percent.   C. 60 percent. D. 92 percent.