| 摘要 | 第1-7页 |
| Abstract | 第7-8页 |
| Chapter One Introduction | 第8-16页 |
| ·Modality | 第8-11页 |
| ·English Modal Verbs | 第11-13页 |
| ·The Significance of the Study | 第13-14页 |
| ·The Structure of the Thesis | 第14-16页 |
| Chapter Two Literature Review | 第16-28页 |
| ·Studies from the View of Traditional Semantics | 第16-19页 |
| ·Studies in Fields of Formal Semantics and General Semantics | 第16-17页 |
| ·Studies from Polysemy and Monosemy Views | 第17-19页 |
| ·Studies from the View of Pragmatics | 第19-22页 |
| ·Modality Study under Speech-Act Theory | 第19-20页 |
| ·Modality Study under Relevance Theory | 第20-21页 |
| ·Modality Study under Adaptation Theory | 第21-22页 |
| ·Studies from the View of Cognitive Linguistics | 第22-24页 |
| ·Talmy’s Study on Modality and English Modal Verbs | 第22-23页 |
| ·Sweetser’s Study on Modality and English Modal Verbs | 第23页 |
| ·Langacker’s Study on Modality and English Modal Verbs | 第23-24页 |
| ·Studies from the View of Historical Linguistics | 第24-26页 |
| ·Summary | 第26-28页 |
| Chapter Three Theoretical Basis | 第28-37页 |
| ·Grammaticalization | 第28-33页 |
| ·Brief Introduction to Grammaticalization | 第28-29页 |
| ·Major Characteristics of Grammaticalization | 第29-31页 |
| ·Mechanisms of Grammaticalization | 第31-33页 |
| ·Inference | 第33-35页 |
| ·The Principle of Least Effort | 第35-37页 |
| Chapter Four Analyses of Semantic Changes in English Modal Verbs | 第37-66页 |
| ·Semantic Changes in English Modal Verbs | 第37-49页 |
| ·The Grammaticalization of English Modal Verbs | 第37-39页 |
| ·Cases Study on English Modal Verbs | 第39-48页 |
| ·The General Regularity of Semantic Changes in English Modal Verbs | 第48-49页 |
| ·Motivations of Semantic Changes in English Modal Verbs | 第49-54页 |
| ·The Effect of Language Contact | 第49-51页 |
| ·The Impact of Language Acquisition | 第51-52页 |
| ·The Influence of Least Effort Principle | 第52-54页 |
| ·Mechanisms of Semantic Changes in English Modal Verbs | 第54-66页 |
| ·Metaphorical Mapping | 第54-57页 |
| ·Conventionalized Inference | 第57-60页 |
| ·Semantic Generalization | 第60-62页 |
| ·Harmonious Unity | 第62-64页 |
| ·Influences of Mechanisms on Different Stages in Semantic Changes | 第64-66页 |
| Conclusion | 第66-69页 |
| Bibliography | 第69-73页 |
| 攻读学位期间发表的学术论文 | 第73-75页 |
| Acknowledgment | 第75页 |
