In addition, I am especially grateful to M.4 students at Assumption Convent
Lamnarai, Lop Buri, who kindly helped me with this study. I wish to thank all my
classmates, my friends, and my boss for their consideration, care and moral
support. Lastly, I would like to give my special thanks to my father, my
mother and all of my family members for their unfailing support during my
studying. Especially, both of my two younger brothers, Mr. Peerapat Yanklang