| Acknowledgements | 第4-5页 |
| Abstract | 第5-6页 |
| 中文摘要 | 第7-12页 |
| Chapter One Introduction | 第12-15页 |
| 1.1 Background of the study | 第12-13页 |
| 1.2 Need of the study | 第13页 |
| 1.3 Significance of the study | 第13-14页 |
| 1.4 The structure of the thesis | 第14-15页 |
| Chapter Two Literature Review | 第15-26页 |
| 2.1 Key terms and basic concepts | 第15-20页 |
| 2.1.1 Definitions of lexical chunks | 第15-17页 |
| 2.1.2 Classification of lexical chunks | 第17-20页 |
| 2.2 Theoretical Bases | 第20-22页 |
| 2.2.1 Krashen's Input Hypothesis | 第20页 |
| 2.2.2 Dual-mode language processing system | 第20-21页 |
| 2.2.3 Chunking theory | 第21-22页 |
| 2.4 Previous studies about lexical chunks home and abroad | 第22-26页 |
| 2.4.1 Previous studies about lexical chunks abroad | 第22-23页 |
| 2.4.2 Previous studies about lexical chunks at home | 第23-26页 |
| Chapter Three Methodology | 第26-33页 |
| 3.1 Research questions | 第26页 |
| 3.2 Research materials | 第26-28页 |
| 3.2.1 Scored compositions of English junior students in the fmal writing examination | 第26-27页 |
| 3.2.2 Translated information from a semi-structure interview | 第27-28页 |
| 3.3 Data Preparation | 第28页 |
| 3.3.1 Scored compositions of English junior students | 第28页 |
| 3.3.2 Translated information from the inerview | 第28页 |
| 3.4 Data Analysis | 第28-33页 |
| 3.4.1 Analysis of Scored compositions of English junior students | 第28-32页 |
| 3.4.2 Analysis of the information from the interview | 第32-33页 |
| Chapter Four Results and Discussion | 第33-44页 |
| 4.1 General characteristics of the use of lexical chunks | 第33-36页 |
| 4.1.1 Total number of lexical chunks and the frequency of using lexical chunks | 第33-34页 |
| 4.1.2 Types of lexical chunks and their proportion distribution | 第34-35页 |
| 4.1.3 Erroneous lexical chunks and their proportion distribution | 第35-36页 |
| 4.2 Diferences of the use of lexical chunks between the high-score group and the low-score group | 第36-40页 |
| 4.2.1 Differences in terms of the total number and the frequency of using lexical chunks between the two groups | 第36-37页 |
| 4.2.2 Differences in terms of the types of lexical chunks between the two groups | 第37-39页 |
| 4.2.3 Differences in terms of the erroneous lexical chunks between the two groups | 第39-40页 |
| 4.3 Correlation between the use of lexical chunks and students' writing scores | 第40-44页 |
| 4.3.1 Correlation between the total number of lexical chunks and the frequency of using lexical chunks and students' writing scores | 第40-41页 |
| 4.3.2 Correlation between the types of lexical chunks and students' writing scores | 第41-42页 |
| 4.3.3 Correlation between the erroneous lexical chunks and students' writing performance | 第42-44页 |
| Chapter Five Conclusion | 第44-48页 |
| 5.1 Major findings | 第44-45页 |
| 5.2 Pedagogical implications | 第45-46页 |
| 5.3 Limitations of the present study | 第46页 |
| 5.4 Suggestions for the future study | 第46-48页 |
| References | 第48-52页 |
| Appendix Ⅰ | 第52-54页 |
| Appendix Ⅱ | 第54-55页 |
| Appendix Ⅲ | 第55-56页 |
| Appendix Ⅳ | 第56-57页 |
