| Acknowledgments | 第1-7页 |
| Abstract | 第7-9页 |
| 摘要 | 第9-10页 |
| Contents | 第10-12页 |
| List of Tables | 第12-13页 |
| List of Figure | 第13-14页 |
| Chapter 1:Introduction | 第14-18页 |
| ·Background of the Study | 第14-15页 |
| ·Significance of the Study | 第15页 |
| ·The Aim of the Study | 第15-16页 |
| ·Research Questions | 第16页 |
| ·Structure of the Study | 第16-18页 |
| Chapter 2:Literature Review | 第18-30页 |
| ·Previous Studies on Hedges | 第18-23页 |
| ·Previous Studies on Hedges Abroad | 第18-21页 |
| ·Previous Studies on Hedges at Home | 第21-23页 |
| ·Previous Studies on American Presidential Debates | 第23-25页 |
| ·Hedges in this Thesis | 第25-30页 |
| Chapter 3:Theoretical Framework | 第30-37页 |
| ·Grice's Cooperative Principle | 第30-33页 |
| ·Four Maxims of Cooperative Principle | 第30-32页 |
| ·Violation of Cooperative Principle | 第32-33页 |
| ·Politeness Principle | 第33-37页 |
| ·Leech's Politeness Principle | 第33-35页 |
| ·Politeness Strategy | 第35-37页 |
| ·Positive Politeness Strategy | 第35页 |
| ·Negative Politeness Strategy | 第35-37页 |
| Chapter 4: Pragmatic Analysis of the Hedges in 2012 American Presidential Debates | 第37-62页 |
| ·Data Collection | 第37-38页 |
| ·Data Presentation | 第38-42页 |
| ·Frequencies of Different kinds of Hedges | 第38-41页 |
| ·Discussion of the Data | 第41-42页 |
| ·Analysis of Hedges from the Perspective of Cooperative Principle | 第42-54页 |
| ·Adaptors and Cooperative Principle | 第42-45页 |
| ·Rounders and Cooperative Principle | 第45-48页 |
| ·Plausibility Shields and Cooperative Principle | 第48-51页 |
| ·Attribution Shields and Cooperative Principle | 第51-54页 |
| ·Analysis of Hedges from the Perspective of Politenes Principle | 第54-56页 |
| ·Hedges Used as Positive Politeness Strategy | 第54-55页 |
| ·Hedges Used as Negative Politeness Strategy | 第55-56页 |
| ·Pragmatic Functions of Hedges in 2012 American Presidential Debates | 第56-62页 |
| ·Being Self-protective | 第56-58页 |
| ·Giving the Right Amount of Information | 第58页 |
| ·Shifting or Avoiding Responsibility | 第58-59页 |
| ·Indicating the Lack of Specific Information | 第59-60页 |
| ·Incresing Credibility | 第60-62页 |
| Chapter 5:Conclusion | 第62-65页 |
| ·Major Findings | 第62-63页 |
| ·Limitations of the Study | 第63-64页 |
| ·Suggestions for Further Research | 第64-65页 |
| References | 第65-67页 |
| AppendiⅠ Hedges in 2012 American Presidential Debates | 第67-68页 |
