| Acknowledgments | 第1-7页 |
| Abstract | 第7-9页 |
| 摘要 | 第9-13页 |
| List of Tables | 第13-14页 |
| Chapter 1 Introduction | 第14-18页 |
| ·Background of the Present Study | 第14-15页 |
| ·Significance of the Study | 第15-16页 |
| ·Overall Structure of the Thesis | 第16-18页 |
| Chapter 2 Literature Review | 第18-39页 |
| ·Definition of Discourse Markers | 第18-19页 |
| ·Properties of Discourse Markers | 第19-21页 |
| ·Functions of Discourse Markers | 第21-27页 |
| ·Subjective Function | 第21-23页 |
| ·Interactional Function | 第23-26页 |
| ·Textual Function | 第26-27页 |
| ·Theoretical Foundation | 第27-34页 |
| ·Coherence Theory | 第27-29页 |
| ·Schiffrin’s Coherence Framework | 第29-34页 |
| ·Previous Study of Relevant Issues | 第34-39页 |
| Chapter 3 The Study | 第39-56页 |
| ·Research Questions | 第39页 |
| ·Data Source | 第39-41页 |
| ·Corpus Data source of Contemporary American English (COCA) | 第39-40页 |
| ·An Introduction to the Spoken Corpus of COCA | 第40-41页 |
| ·Data Processing | 第41-44页 |
| ·Antconc | 第41-42页 |
| ·Data Processing Procedure | 第42-44页 |
| ·Data Analysis | 第44-56页 |
| ·Quantitative Analysis of Data | 第44-49页 |
| ·Qualitative Analysis of Data | 第49-56页 |
| Chapter 4 Results and Discussions | 第56-74页 |
| ·Results | 第56-61页 |
| ·The Frequencies of “Now” and “Then” in the Realization of the Subjective, Interactional and Textual Functions | 第56-59页 |
| ·The Distribution of “Now” and “Then” in the Realization of the Subjective, Interactional and Textual Functions | 第59页 |
| ·The Role of “Now” and “Then” in the Realization of the Subjective, Interactional and Textual Functions | 第59-61页 |
| ·Discussions | 第61-74页 |
| ·Discussion of the Frequencies of “Now” and “Then” | 第61-62页 |
| ·Discussion of the Distribution of “Now” and “Then” | 第62-63页 |
| ·Discussion of Functions of “Now” and “Then” in Schiffrin’s Framework | 第63-74页 |
| Chapter 5 Conclusion | 第74-77页 |
| ·Major Findings | 第74-75页 |
| ·Limitations and Suggestions for Further Study | 第75-77页 |
| References | 第77-78页 |
