D Our surroundings are being polluted faster than ever and it seems that people cannot prevent it. Time is bringing us more people, and more people will bring us more industry', more cars, larger cities, and the growing use of man-made materials. What can explain and settle this problem? The fact is that pollution is caused by man—by his desire (欲望) for a modem way of life. We make 'increasing industrialization' (工业化) our first aim. So we are often ready to offer everything: clean air, pure water, good food, our health and the future of our children. There is a constant flow of people from the countryside into the cities, eager for the achievements of our modem society. But as our technological achievements have grown in the last twenty years, pollution has become a serious problem. Isn't it time we stopped to ask ourslves where we are going—and why? It makes one think of the story about the pilot (飞行员) who told his passengers over the loudspeaker: 'I've some good news and some bad news. The good news is that we're making rapid progress at 530 miles per hour. The bad news is that we are lost and don't know where we're going.' The sad fact is that this becomes a true story when speaking of our modern society. Man cannot prevent the world from being polluted because ______.