I am indebted to the many people who made this thesis possible.
First and foremost, my deepest gratitude goes to my advisor Dr. Ali Gholami Mehrdad. This thesis would not have been possible without his guidance. His inspiration, motivation, immense knowledge, and enthusiasm in research have motivated all his advisees, including me. Also, I would like to thank my honorable reader Dr. Dariush Ahmadi for taking time to read through the report and to provide useful and praiseworthy suggestions.
I am most grateful to Mrs. Sudabeh Shamsabadi and her students at Iran Language Institute who participated patiently and eagerly in this study.
Last, but not the least, I owe more than thanks to my husband, Shahriyar Rahnama and my parents, Mohammad Nateghi Moghadam and Giti Vahidi Nasab, whose patience, love, support and encouragement enabled me to complete this study.
Niloofar Nateghi Moghadam