Abstarct: Acknowledgments First of all, I thank God from the bottom of my heart for helping me along the way. Then I would like to express my great thankfulness to my beloved family. There is no doubt that this thesis has not been possible without the love, motivation, and encouragement of my family and my husband who patiently continued to support me throughout the entire process to complete the project. Above and beyond, I express my gratefulness and appreciation to my supervisor Dr. Mozaffari and my advisor Dr. Ostovar who generously provided me with their valuable guidance. I would also like to express my special thanks of gratitude to Dr. Iranmehr, the Head of the Department and all the valuable professors who helped me in my academic progress, as well as all the language learners who sincerely participated in the classes and helped me to provide data for my study.