听力原文： Scientists in many developing nations are studying a way to protect and control the use of forests, fishing water, grasslands and other resources. They call the system 'common property'. It means that people join together to abate and protect the resources. Scientists say that increased population is damaging the world resources. Too many trees are cut; grasslands and croplands are destroyed. Too many fish are taken from the fishing area. There are two traditional ways to deal with this situation. One is public: the government agency decides who may use the resources and when; or the property can be private: the owner decides how to protect the resources. Experts say these two methods often are not effective, however. They believe there is a third possibility that is neither completely governmental nor completely private. It is communal or joint control of the resources. Scientists know that this idea of common property is not new. The system has been believed successful for a long time by groups in many countries. In South Asia, some villagers have governing systems to protect everyone's right to irrigation water. In part of Central Africa, there are traditional rules that banned the killing of some wild animals. Farmers in Syria have a system to share grasslands and fisherman in Turkey have a system to make sure no one takes too many fish. Scientists say such systems usually were developed by small groups to deal with limited problems. Rules are simple and the enforcement is based on traditional value and ways of doing things. Scientists believe such systems also would be effective in other situations. They are studying how it might produce more cooking rules for people in Indian villages. The scientific group in Costa Rice is studying common property to control land area. And a government group in Zimbabwe is studying the system to protect wild animals. Scientists do not say the common property system will solve all resource needs in developing nations, buy they believe it provides one important way to deal with the problem. (33)