| Abstract （Chinese） | 第1-8页 |
| Abstract （English） | 第8-10页 |
| Acknowledgements | 第10-12页 |
| List of tables and figures | 第12-14页 |
| Chapter Ⅰ Introduction | 第14-18页 |
| Chapter Ⅱ Literature Review | 第18-46页 |
| 2．1 Introduction to chapter Ⅱ | 第18页 |
| 2．2 Schools of thought in ESL writing | 第18-19页 |
| 2．3 The development of writing instruction | 第19-26页 |
| 2．3．1 The product approach | 第19-21页 |
| 2．3．2 The process approach | 第21-24页 |
| 2．3．3 Advocacy of task-based instruction in writing | 第24-26页 |
| 2．4 Theories concerning task and task-based instruction | 第26-39页 |
| 2．4．1 Definitions of task | 第26-29页 |
| 2．4．2 Task-based instruction | 第29-30页 |
| 2．4．3 The implementation of task-based instruction | 第30-35页 |
| 2．4．3．1 Task-based teaching material development | 第31-32页 |
| 2．4．3．2 Frameworks of the implementation of task-based instruction | 第32-35页 |
| 2．4．4 Rationales for task-based instruction | 第35-37页 |
| 2．4．4．1 Psycholinguistic rationale for task-based instruction | 第35-36页 |
| 2．4．4．2 Rationale from conditions for language learning | 第36-37页 |
| 2．4．5 Goals to achieve in task-based instruction | 第37-39页 |
| 2．5 The assessment of writing | 第39-44页 |
| 2．5．1 Criteria for successful writing | 第39-40页 |
| 2．5．2 Ways to assess writing | 第40-44页 |
| 2．5．2．1 Holistic scoring | 第40-41页 |
| 2．5．2．2 Discourse indexes | 第41-43页 |
| 2．5．2．3 Writing behavior observation | 第43-44页 |
| 2．6 Current studies on task-based instruction in writing | 第44-46页 |
| Chapter Ⅲ The Study | 第46-67页 |
| 3．1 Research questions and hypotheses | 第46-48页 |
| 3．2 Methods | 第48-54页 |
| 3．2．1 Definitions of Variables | 第48-50页 |
| 3．2．1．1 Definitions of the independent variables | 第48-49页 |
| 3．2．1．2 Definitions of the dependent variables | 第49-50页 |
| 3．2．2 Subjects | 第50-52页 |
| 3．2．3 Procedures of material development | 第52-54页 |
| 3．2．3．1 Material development for EG | 第52-53页 |
| 3．2．3．2 Material development for CG1 | 第53-54页 |
| 3．2．3．3 Material development for CG2 | 第54页 |
| 3．3 Procedures of the study | 第54-58页 |
| 3．4 Raw data collection | 第58页 |
| 3．5 Coding | 第58-66页 |
| 3．5．1 Scoring the essays | 第58-62页 |
| 3．5．1．1 The pilot scoring | 第58-61页 |
| 3．5．1．2 The actual scoring | 第61-62页 |
| 3．5．2 Coding for discourse indexes | 第62-65页 |
| 3．5．3 Coding for retrospective questionnaires | 第65-66页 |
| 3．6 Statistical analyses of the data | 第66-67页 |
| Chapter Ⅳ Results and Discussion | 第67-90页 |
| 4．1 Results in relation to research question Ⅰ | 第67-70页 |
| 4．2 Results in relation to research question Ⅱ | 第70-75页 |
| 4．2．1 Results in relation to fluency | 第72-73页 |
| 4．2．2 Results in relation to complexity | 第73-74页 |
| 4．2．3 Results in relation to accuracy | 第74-75页 |
| 4．3 Results in relation to research question Ⅲ | 第75-82页 |
| 4．3．1 Overall description of the writing behavior shown by the three groups | 第75-77页 |
| 4．3．2 Further illustration of the differences | 第77-82页 |
| 4．3．2．1 Different writing behavior between EG and CG1 | 第77-79页 |
| 4．3．2．2 Different writing behavior between EG and CG2 | 第79-82页 |
| 4．4 Summary of the results | 第82页 |
| 4．5 Discussion | 第82-90页 |
| 4．5．1 Why can task-based instruction promote writing development most significantly | 第82-86页 |
| 4．5．2 Why can task-based instruction result in better interlanguage development | 第86-88页 |
| 4．5．3 Why is task-based instruction more facilitative in writing strategy training | 第88-90页 |
| Chapter Ⅴ Conclusion | 第90-95页 |
| 5．1 Major findings of the study | 第90页 |
| 5．2 Pedagogical implications | 第90-92页 |
| 5．3 Limitations of the present study | 第92-93页 |
| 5．4 Suggestions for further research | 第93-95页 |
| References | 第95-101页 |
| Appendices | 第101-123页 |
| Appendix 1: Selected argument topics from the students | 第101-102页 |
| Appendix 2a: Teaching materials for EG | 第102-106页 |
| Appendix 2b: Teaching materials for CG1 | 第106-108页 |
| Appendix 2c: Teaching materials for CG2 | 第108-112页 |
| Appendix 2d: Checklist for peer revising distributed to EG and CG1 | 第112-114页 |
| Appendix 3: Post-writing retrospective questionnaire | 第114-115页 |
| Appendix 4: Sample essays from holistic scoring | 第115-117页 |
| Appendix 5: Holistic scores of pretest and posttest | 第117-118页 |
| Appendix 6a: Discourse indexes of EG's essays | 第118-119页 |
| Appendix 6b: Discourse indexes of CG1's essays | 第119-120页 |
| Appendix 6c: Discourse indexes of CG2's essays | 第120-121页 |
| Appendix 7a: Coding of the writing behavior of EG | 第121-122页 |
| Appendix 7b: Coding of the writing behavior of CG1 | 第122-123页 |
| Appendix 7c: Coding of the writing behavior of CG2 | 第123页 |
