The farewell day would the least expected day in my life, but it has come eventually. At this momnet, I have to say that it is such a priviliage and honor to have worked with you guys shoulder on shouldr over the last four years. We went through a lot and achieved a lot. When I look back and think about the past, I feel so pround and accomplished not only because of the knowledge I have learnt and the progress I have made in my study, but also because the geniue friendship I have obtained with you guys.