| Acknowledgements | 第4-6页 |
| Academic Achievements | 第6-7页 |
| 摘要 | 第7-9页 |
| Abstract | 第9-11页 |
| Abbreviation | 第18-21页 |
| Chapter One Introduction | 第21-25页 |
| 1.1 Research Background | 第21-22页 |
| 1.2 Research Questions | 第22-23页 |
| 1.3 The Structure of the Thesis | 第23-25页 |
| Chapter Two Literature Review | 第25-40页 |
| 2.1 Overseas Studies on Null Subjects in L2 Acquisition | 第25-33页 |
| 2.1.1 Studies within the Theoretical Framework of the Pro-drop Parameter (the Null Subject Parameter) | 第25-29页 |
| 2.1.2 Studies within the Theoretical Framework of the Morphological Uniformity Principle | 第29-30页 |
| 2.1.3 Studies within the Theoretical Framework of Linguistic Typology | 第30页 |
| 2.1.4 Studies within the Theoretical Framework of the Minimalist Program | 第30-33页 |
| 2.2 Overseas Studies in L2 Acquisition concerning Expletive it | 第33-36页 |
| 2.3 Domestic Studies in L2 Acquisition concerning Expletive it | 第36-39页 |
| 2.4 Summary | 第39-40页 |
| Chapter Three Theoretical Backgrounds | 第40-50页 |
| 3.1 The Theory of Universal Grammar | 第40-41页 |
| 3.2 Role of Universal Grammar in Second Language Acquisition | 第41-42页 |
| 3.3 Differences between English and Chinese | 第42-47页 |
| 3.3.1 Differences in the Pro-drop Parameter Aspect | 第42-44页 |
| 3.3.2 Differences in the Language Typology Aspect | 第44-47页 |
| 3.4 The Subset Principle | 第47-49页 |
| 3.5 Summary | 第49-50页 |
| Chapter Four Empirical Study | 第50-79页 |
| 4.1 Hypotheses | 第51-52页 |
| 4.2 Subjects | 第52-53页 |
| 4.3 Tasks | 第53-55页 |
| 4.4 Scoring | 第55-56页 |
| 4.5 Results | 第56-77页 |
| 4.5.1 Difference among Learning of Expletive it in Four Contexts | 第57-64页 |
| 4.5.2 Difference among Three groups of Chinese Learners | 第64-70页 |
| 4.5.3 Difference between Learning of Expletive it in Matrix and Embedded Sentences | 第70-74页 |
| 4.5.4 Error Patterns Made by Three Groups in Learning of Expletive it in Four Contexts | 第74-77页 |
| 4.6 Summary | 第77-79页 |
| Chapter Five Discussion | 第79-96页 |
| 5.1 Performance Difference among Three Groups in Learning of Expletive it | 第79-82页 |
| 5.2 Performance Difference among Expletive it in Four Contexts | 第82-85页 |
| 5.3 Performance Difference between Expletive it in Matrix and Embedded Sentences | 第85-87页 |
| 5.4 Literal Translation and There Overuse in the Acquisition of Expletive it by Chinese Learners | 第87-94页 |
| 5.4.1 Literal Translation in the Acquisition of Expletive it by Chinese Learners | 第87-90页 |
| 5.4.2 There Overuse in the Acquisition of Expletive it by Chinese Learners | 第90-94页 |
| 5.5 Summary | 第94-96页 |
| Chapter Six Conclusion | 第96-100页 |
| 6.1 Summary of the Whole Study | 第96-97页 |
| 6.2 Pedagogical Implications | 第97-98页 |
| 6.3 Limitations of the Study and Suggestions for Future Research | 第98-100页 |
| References | 第100-105页 |
| Appendices | 第105-110页 |
| Appendix One | 第105-108页 |
| Appendix Two | 第108-110页 |
