This paper presents a novel study and analysis on two important problems in gait recognition: one is how to perform gait recognition with only segment of a complete gait cycle for test and the other is how static and dynamic information affect the recognition results in such situation. In conventional gait recognition research, the gait sequence of at least one cycle is usually needed to ensure the completeness of gait dynamics. And in this paper we will show that this is not a necessary condition and considerable recognition results could still be achieved with only part of the cycle based on appropriate similarity measure algorithms. Moreover, we will also show the different roles that static and dynamic information play in such situation through experimental study. To our knowledge, there is little work on these important problems, results from which can make gait recognition more applicable in frequently happened scenarios such as occlusion.