[1]   2002.6 to  Now
Peking University  | Professor
[2]   1997.1  to  2002.7
Peking University  | Associate Professor
[3]   1991.6  to  1993.6
Gran Sasso Cosmic Ray Laboratory, Italy  | Visiting Scientist
[4]   1989.6  to  1991.5
Peking University  | Lecturer
[5]   1987.1  to  1989.7
Peking University  | Teaching Assistant