2 Theories and Challenges In this part, theoretical basis will first be established through general introduction to Cooperative Principle and Relevance Theory. Challenges will then be stated by discussing the two theories’ limitations and restrictions. 2.1 Cooperative Principle 2.1.1 General Introduction to CP Cooperative Principle was first presented by American language philosopher H.P.Griceat when he was giving the speech “Logic and Conversation” at Harvard University. He believes that in all language communication, the speaker and the listener tend to have a tacit cooperation. In order to ensure a smooth conversation, they always intentionally or unintentionally abide by a basic principle -- that is, people will provide appropriate words according to changes of a conversation’s purpose or direction once they participate in one. Cooperative Principle provides a new approach to the understanding of discourse communication, shifts the perspective of research from static semantic analysis to dynamic pragmatic analysis and thus makes linguistic research closer to the rich and varied real life. 2.1.2 The Four Maxims of Cooperative Principle Grice argues that the Cooperative Principle can be divided into four maxims: "quality", "quantity", "relevance", and "manner", each of them comprising some sub-criteria which can be summed up as follow: （1）Quality Maxim: ① All the information that a communicator conveys must be true. ② Information lacking of adequate evidence should be