下面小编跟大家一起了解英语四级新闻听力讲解，希望对大家的学习有所帮助
一、听力练习
　　1.
　　A. A fire retardant that can stop or slow the spread of fires.
　　B. An alarming system that can detect wildfires.
　　C. A material that is fire-proof.
　　D. A long-lasting, environmentally safe substance that can prevent wildfires from spreading.
　　2.
　　A. Because of environmental and weather conditions.
　　B. Because of burning of flames.
　　C. Because of smoke caused by wildfires.
　　D. Because of water shortage.
　　二、听力文本
　　Researchers have developed a long-lasting, environmentally safe substance that can prevent wildfires from spreading. The Stanford team says the treatment could give firefighters a valuable weapon in their battle against wildfires. The researchers sought to find a substance that could be deployed to such areas to stop fires from starting in the first place. Firefighters often use chemical fire retardants to put out fires. Fire retardants are materials that can stop or slow the spread of fires. But firefighting crews currently use them only as a kind of reactive tool. This is because the chemical treatments are not designed to stay on trees or other vegetation for long periods. They can quickly disappear because of environmental and weather conditions. The thick liquid tested by the Stanford University team was found to extend the life of the fire retardants without harming the environment. Such a treatment could open up possibilities for firefighters to take preventive actions before fires even start. The testing found that the material "provides complete fire protection even after half an inch of rainfall," the study said. Under the same conditions, commonly used fire retardants provided little or no protection from fire. The researchers said they continue to test the treatment with state transportation and fire officials. This includes one of the biggest high-risk areas for the start of wildfires: roadsides. The development team says the treatment contains only safe materials widely used in food, drug and agricultural products. Over time, the material washes away and breaks down safely in the environment, the researchers noted.
　　Question 1: According to the news report, what have researchers developed?
　　Question 2: According to the news report, why do chemical treatments quickly disappear?
　　三、重点词汇
　　1. substance: material with particular physical characteristics 物质；材料
　　2. deploy: to use something or someone, especially in an effective way 有效运用；发挥…的作用
　　3. retardant: (a substance) that makes the progress or growth of something slower 起阻滞作用的，阻止的；阻滞剂，阻化剂
　　4. reactive: reacting to events or situations rather than acting first to change or prevent something 反应的，回应的（非主动求变或预防性的）
　　5. preventive: intended to stop something before it happens 防止的，预防的