I was totally shocked and extremely sad about your early departure from life. You are gone. I was planning to discuss with you this Monday afternoon, but the opportunity to learn from you in person is no longer possible. Although I came here less than five months, I treasure every opportunity to meet you at your office to discuss with you. And I have learnt a lot from you. You are a sharp, rigorous, precise, selfless and knowledgeable researcher and supervisor. Although I was often criticized by you, I was clear that everything you have done were useful and helpful to me. Although I am just a visiting student and you are the busiest teacher, you have spent much time on me to help me correct bad academic habits and provide much guidance on my research work. I am really full of gratitude to you. I will keep your advice in mind. I know you never care how we think of you. Everything you were doing and had done were all based on your own principle: honest, integrity, selflessness, and kindness. You treat all our students like your own family members, cared and supported us as much as you could. You are one of my greatest and dearest teacher I have met. Now you have gone but one thing for sure is that you won’t be forgotten. Dear professor Li, you will be missed, respected and loved forever. May you rest in peace, our dearest professor.