| Acknowledgements | 第1-6页 |
| Abstract | 第6-8页 |
| 摘要 | 第8-12页 |
| Chapter 1 Introduction | 第12-18页 |
| ·Background of the Study | 第12-14页 |
| ·Significance of the Study | 第14-15页 |
| ·Overall Structure of the Thesis | 第15-18页 |
| Chapter 2 Literature Review | 第18-36页 |
| ·Polysemy | 第18-24页 |
| ·The Definition of Polysemy | 第18-19页 |
| ·Polysemy, Homonymy and Monosemy | 第19-20页 |
| ·Traditional Approaches to Polysemy | 第20-23页 |
| ·Cognitive Approach to Polysemy | 第23-24页 |
| ·Prototype Theory and Categorization | 第24-29页 |
| ·The Classical Approach of Categorization and Its Inadequacies | 第25-26页 |
| ·The Alternative Approach — Prototypes | 第26-29页 |
| ·The Prototypical Sense and Polysimic Semantic Extension | 第29-34页 |
| ·Prototypical Sense and Derivation of Non-prototypical Members | 第29-30页 |
| ·Cognitive Devices of Polysimic Semantic Extension | 第30-34页 |
| ·The Study on Prepositional Polysemy at Home and Abroad | 第34-36页 |
| Chapter 3 Research Design | 第36-43页 |
| ·Research Questions | 第36页 |
| ·Data Collection | 第36-37页 |
| ·The Selection of “Over” as the Objective | 第36-37页 |
| ·The Retrieval of “Over” in BNC | 第37页 |
| ·Data Presentation | 第37-43页 |
| Chapter 4 A Prototype Theory –based Study on “Over” | 第43-69页 |
| ·The Prototypical Sense of “Over” and Its Semantic Extension | 第43-58页 |
| ·The Prototypical Sense of “Over” | 第43-47页 |
| ·The Prototypical Image Schema of “Over” | 第47-49页 |
| ·The Semantic Extension of the Prototypical Sense of “Over” | 第49-58页 |
| ·The Prototype-centered Semantic Network of “Over” and the Relevance of Different Meanings of “Over” | 第58-66页 |
| ·The Prototype-centered Semantic Network of “Over” | 第59-60页 |
| ·The Relevance of Different Meanings of “Over” | 第60-66页 |
| ·The Reasons for the Formation of Polysemy | 第66-69页 |
| ·The Principle of Economy of Language | 第66-67页 |
| ·The Semantic Extension | 第67-69页 |
| Chapter 5 Conclusion | 第69-71页 |
| ·Major Findings of the Research | 第69-70页 |
| ·Limitations of the Research and Suggestions for Further Study | 第70-71页 |
| References | 第71-73页 |
