听力原文：W: The more I learn about the world around me, the more I am aware of the problems facing us. M: Do you mean the problems here in China? W: Yes, here and all over the world. M: Well, there's one problem I'm certainly aware of and that is the environmental pollution all around us. W: That is one of the great problems, but in many parts of the world, as people become more aware and apply new technology to solving the pollution problem, there is hope for the future. M: What technology will help with pollution control? W: Well, for example, I've recently read an article about using certain types of bacteria to help control some pollution problems. M: How could that be? I thought bacteria just caused illness. W: That's not true. Scientists have identified certain bacteria that 'eat' petroleum products, such as oil and gasoline. M: That sounds very strange. How does it work? W: They cat the petroleum and excrete hydrogen and oxygen, leaving a clean environment behind them. M: Could they use those little bugs to clean up big oil spills? W: Yes, as a matter of fact, they are being proven to be the most successful method of cleaning land-based oil spills and are also useful for marine spills. M: Wow! Are there other types of pollution those bacteria like to eat? W: Sure, bacteria have been used to remove arsenic from the sludge produced by gold mining operations. There are even experiments being done now to reduce nuclear waste to a harmless residue. M: Maybe those bacteria that we used to worry about will eventually save the world! (20)