| Acknowledgements | 第1-5页 |
| Abstract | 第5-7页 |
| 内容摘要 | 第7-11页 |
| Chapter One Introduction | 第11-18页 |
| ·Modality and English Modal Auxiliaries | 第11-14页 |
| ·Significance of the Study | 第14-16页 |
| ·Organization of the Thesis | 第16-18页 |
| Chapter Two Literature Review | 第18-29页 |
| ·Traditional Grammatical Study | 第18-20页 |
| ·Semantic Study | 第20-22页 |
| ·Pragmatic Study | 第22-23页 |
| ·Systemic-functional Grammar and Cognitive Grammar Study | 第23-27页 |
| ·Limitations of Previous Study | 第27-29页 |
| Chapter Three Theoretical Background | 第29-41页 |
| ·Talmy's Force Dynamics | 第29-31页 |
| ·Metaphorical Mapping | 第31-35页 |
| ·The Importance of Meaning Construction | 第31-33页 |
| ·Metaphorical Mapping in Thought and Language | 第33-35页 |
| ·Mental-space Theory | 第35-41页 |
| ·Meaning, Language and Cognition | 第35-36页 |
| ·Mental Spaces | 第36-41页 |
| ·Definition of mental space | 第36-37页 |
| ·Space-builders | 第37-38页 |
| ·Connectors and counterparts | 第38-41页 |
| Chapter Four The Mental-space Theoretical Analysis of Polysemy of Modality | 第41-67页 |
| ·The Polysemic View of English Modal Verbs | 第41-47页 |
| ·The View of Monosemy | 第41-42页 |
| ·The View of Ambiguity | 第42-44页 |
| ·The View of Polysemy | 第44-47页 |
| ·Deontic modality | 第44-45页 |
| ·Epistemic modality | 第45-47页 |
| ·The Extension of Deontic Modality to Epistemic Modality | 第47-53页 |
| ·Two Spaces of Modal Semantics | 第47-49页 |
| ·The Priority of Deontic Modality | 第49-50页 |
| ·Metaphorical Mapping from Deontic Modality to Epistemic Modality | 第50-53页 |
| ·The Interpretation of English Modal Verbs | 第53-67页 |
| ·The Semantics and Interpretation of MUST | 第53-56页 |
| ·The Semantics and Interpretation of MAY | 第56-58页 |
| ·The Semantics and Interpretation of CAN | 第58-61页 |
| ·The Semantics and Interpretation of SHOULD | 第61-63页 |
| ·The Semantics and Interpretation of WILL | 第63-67页 |
| Chapter Five Conclusion | 第67-70页 |
| ·Summary of the Study | 第67-68页 |
| ·Limitations and Suggestions | 第68-70页 |
| References | 第70-73页 |
