| 摘要 | 第5-6页 |
| ABSTRACT | 第6页 |
| List of Abbreviations | 第7-11页 |
| Chapter One Introduction | 第11-15页 |
| 1.1 Research Background | 第11-12页 |
| 1.2 Purpose and Significance of the Study | 第12-13页 |
| 1.3 Research Questions | 第13页 |
| 1.4 Layout of the Thesis | 第13-15页 |
| Chapter Two Literature Review | 第15-27页 |
| 2.1 Lexical Richness | 第15-21页 |
| 2.1.1 Classification of Lexical Richness | 第15-17页 |
| 2.1.2 Aspects of Lexical Richness | 第17-21页 |
| 2.1.2.1 Lexical Variation | 第17-19页 |
| 2.1.2.2 Lexical Density | 第19-20页 |
| 2.1.2.3 Lexical Sophistication | 第20-21页 |
| 2.2 Previous Studies | 第21-27页 |
| 2.2.1 Previous Studies on Lexical Richness | 第22-23页 |
| 2.2.2 Previous Studies on EFL Learners | 第23-27页 |
| Chapter Three Research Methodology | 第27-36页 |
| 3.1 Corpus-based Approach | 第27-29页 |
| 3.2 Corpora and Instruments | 第29-32页 |
| 3.3 Research Procedures | 第32-36页 |
| 3.3.1 Research Design | 第32-33页 |
| 3.3.2 Data Collection | 第33-34页 |
| 3.3.3 Data Analysis | 第34-36页 |
| Chapter Four Results and Discussion | 第36-64页 |
| 4.1 Comparison of Lexical Variation | 第36-45页 |
| 4.1.1 Comparison Between Chinese English Majors and Native Speakers | 第36-39页 |
| 4.1.2 Comparison Among Chinese English Majors | 第39-44页 |
| 4.1.3 Comparison Between High Grade Students'Spoken English and Low Grade Students' Written English | 第44-45页 |
| 4.2 Comparison of Lexical Density | 第45-53页 |
| 4.2.1 Comparison Between Chinese English Majors and Native Speakers | 第46-47页 |
| 4.2.2 Comparison Among Chinese English Majors | 第47-52页 |
| 4.2.3 Comparison Between High Grade Students' Spoken English and Low Grade Students' Written English | 第52-53页 |
| 4.3 Comparison of Lexical Sophistication | 第53-62页 |
| 4.3.1 Comparison Between Chinese English Majors and Native Speakers | 第54-56页 |
| 4.3.2 Comparison Among Chinese English Majors | 第56-60页 |
| 4.3.3 Comparison Between High Grade Students' Spoken English and Low Grade Students' Written English | 第60-62页 |
| 4.4 Summary | 第62-64页 |
| 4.4.1 Comparison Between English Majors and Native Speakers | 第62页 |
| 4.4.2 Comparison Among English Majors | 第62-63页 |
| 4.4.3 Comparison Between High Grade students' Spoken English and Low Grade Students' Written English | 第63-64页 |
| Chapter Five Conclusion | 第64-69页 |
| 5.1 Major Findings | 第64-66页 |
| 5.2 Implications | 第66-68页 |
| 5.3 Limitations and Suggestions for Further Study | 第68-69页 |
| References | 第69-75页 |
| Acknowledgments | 第75-77页 |
| Resume | 第77页 |
