The special Bahncard problem is the generalization of the Ski-Rental problem.

It abandons the study of Kafka issues in an all-round way, and analyzes the two points of deconstructing Kafka issues according to the ‘time-development’ line and the tendency of the development of Kafka s personality and the mysterious phenomenon of Kafka.

This article selected one classical selection task as the experimental material, adopted specific examples representation and categorized representation, used specialists (mathematic teachers in college) as participants and studied the mechanism of the effect of representation and mathematic-logical schema on the selection task.