This thesis reconsiders some theoretical ideas of the communicative approach , four key concepts in particular , underlying one of its teaching principles claiming that language is a tool for communication and the ultimate goal of language teaching is to enable language learners to acquire " communicative competence " , which means to use the target language appropriately to communicate with different people on social occasions of various kinds 交际教学法提出： “语言是交际工具，语言教学的目的是通过语言来学习交际，获得交际能力，即能够运用所学语言在不同的场合中对不同的对象进行有效的、得体的交际” (李观仪， 1989 ) 。
This thesis is composed of four parts as follows : part i focuses on the review of the history of the cud . this part analyses the connotation of the cud , and , through the review of the system of the cud of various countries , combined with china ' s civil legislation , reaches the conclusion that the cud in china ' s contract law equals to creditors " contract , based on which demonstrates the inaccurate cognition of the validity of the cud in the academic field , which paves the way for other parts . part n argues that the cud in china ' s contract law equals to creditors " contract 全文共分四个部分第一部分：对于无权处分行为的历史考察本部分从处分的概念入手，界定了处分行为的内涵，指出其在不同的场合有不同的独特含义，通过考察不同国家的无权处分行为制度，对主要大陆法系国家的无权处分行为作了具体的结论，得出我国合同法上的无权处分行为指的是无处分权人以自己的名义与相对人订立的债权合同的结论，并在此基础上论证了我国理论界对无权处分行为的错误认识，指出了无权处分行为无效说、效力区别说和效力未定说的不足，为下文打下了伏笔。
