| Chapter 1 Introduction | 第1-12页 |
| Chapter 2 Literature review | 第12-17页 |
| Chapter 3 The MM's theoretical sources in linguistics | 第17-24页 |
| ·Rational linguistic choices: support from the means-end model | 第17-18页 |
| ·More costs in marked varieties: support from the markedness theory | 第18-21页 |
| ·Economically biased cognitive calculations: support from Zipfs law | 第21-22页 |
| ·Summary | 第22-24页 |
| Chapter 4 Discourse roles and their switching | 第24-36页 |
| ·An overview of discourse roles and their switching | 第24-26页 |
| ·Types of discourse roles: definition by Jenny Thomas | 第26-27页 |
| ·Refinements into the definition | 第27-32页 |
| ·The "speaker" | 第28页 |
| ·The "author" | 第28-29页 |
| ·The "reporter" and the "mouthpiece" | 第29-31页 |
| ·The "spokesperson" | 第31-32页 |
| ·Other considerations in the identification of discourse roles | 第32-34页 |
| ·Summary | 第34-36页 |
| Chapter 5 The switching of discourse roles under the MM | 第36-61页 |
| ·Discourse roles and their switching under the MM: a general hypothesis | 第36-37页 |
| ·Criteria for markedness of discourse roles | 第37-38页 |
| ·Data collection | 第38-40页 |
| ·Data analysis | 第40-43页 |
| ·"Speaker": the unmarked discourse role | 第40-42页 |
| ·Front position: the unmarked position for the message-introducer | 第42-43页 |
| ·Marked choices of discourse roles and their pragmatic effects | 第43-57页 |
| ·Marked choice of "speaker" | 第44-46页 |
| ·Marked choice of "author" | 第46-49页 |
| ·Marked choice of "reporter" | 第49-54页 |
| ·Marked choice of "mouthpiece" | 第54-56页 |
| ·Marked choice of "spokesperson" | 第56-57页 |
| ·Summary | 第57-61页 |
| Chapter 6 Concluding remarks | 第61-65页 |
| ·Conclusion | 第61-63页 |
| ·Possible implications | 第63-64页 |
| ·Further studies | 第64-65页 |
| Bibliography | 第65-69页 |
| Appendix | 第69-70页 |
