| Acknowledgements | 第1-6页 |
| 摘要 | 第6-8页 |
| Abstract | 第8-13页 |
| Chapter 1 Introduction | 第13-17页 |
| Chapter 2 Literature Review | 第17-27页 |
| ·Definition of Vagueness | 第17-18页 |
| ·Previous Studies of Vagueness | 第18-21页 |
| ·Previous Studies of Vagueness Abroad | 第18-20页 |
| ·Previous Studies of Vagueness in China | 第20-21页 |
| ·Definition and Features of PC | 第21页 |
| ·Definition and Functions of PCL | 第21-22页 |
| ·Previous Studies of Vagueness in PCL | 第22-23页 |
| ·Previous Studies of CP and PP | 第23-27页 |
| Chapter 3 Theoretical Framework | 第27-37页 |
| ·Cooperative Principle | 第27-30页 |
| ·The Conversational Implicature | 第30-31页 |
| ·Politeness Principle | 第31-34页 |
| ·Concepts in Classifications of Vagueness in PCL | 第34-37页 |
| ·Semantic Vagueness | 第34-36页 |
| ·Pragmatic Vagueness | 第36-37页 |
| Chapter 4 Analysis of Vagueness in American Presidents' Remarks in PCL from the Perspectives of CP and PP and Its Communicative Functions | 第37-60页 |
| ·Quantitative Analysis of Data | 第37-39页 |
| ·Analysis of Vagueness from the Perspective of CP | 第39-46页 |
| ·Observance of Maxims of CP | 第39-41页 |
| ·Violation of Maxims of CP | 第41-46页 |
| ·Production of Conversational Implicature in PCL | 第46-48页 |
| ·Analysis of Vagueness from the Perspective of PP in PCL | 第48-55页 |
| ·Communicative Functions of Vagueness in PCL | 第55-60页 |
| ·Providing an Appropriate Amount of Information | 第55-56页 |
| ·Withholding Information Intentionally | 第56-57页 |
| ·Self-protecting | 第57-59页 |
| ·Achieving Politeness | 第59-60页 |
| Chapter 5 Conclusion | 第60-62页 |
| Bibliography | 第62-67页 |
| Appendix | 第67-68页 |
| Papers Published During the Study for M.A. Degree | 第68页 |
