我早就认识程教授,但在初期,与他较深的接触,不是面对面,而是我和我的学生们学习他的专著:《非线性系统的几何理论》,北京,科学出版社,1988.以后,在有关学术会议上经常见面,也逐渐熟悉、交深,常年看到他的不断发表在学术刊物上的论文.到北京开会,看到他时也总是受到他的热情接待.交往日久,我感到他是一位正直、热情、永不停歇进行研究和探索的学者. I had known Prof. Cheng long ago, but in the early days he was in deeper contact with him rather than face-to-face, but I and my students studied his monograph: “Geometric Theory of Nonlinear Systems”, Beijing Science Press, 1988 Since then, he has been familiar with and frequently acquainted with relevant academic conferences, paying deep visits to his perennial papers published in academic journals, meeting with him in Beijing and always receiving his warm reception when seeing him. As time goes on, I feel he is a righteous, enthusiastic, never stop research and exploration scholars.