support. I am grateful to my colleagues for their help. I would also like to thank the large and great Chinese community at ITC. I enjoyed the happy time that I spent with all of you, and I will remember every Chinese festival we celebrated together.I would like to thank my parents, especially my mother. Even though we are 9,000 kilometers apart, she always encourages and supports me. I also want to express my gratitude to Pastor Chung, his spouse, and many brothers and sisters in the Netherlands, Germany, and China. Besides, I would like to thank my Master's supervisor Prof. Lin Zhang, for leading me to the door of research.The COVID-19 pandemic, natural disasters, wars... Four years is not a long time in one's life, but I am sure I will remember many things that happened during those four years for the rest of my life. May we have peace and joy each and every day, and I hope to meet many of you in the near future.