A. Positive reinforcement
B. Negative reinforcement
C. Punishment
D. vicarious reinforcement
The analysis of this problem examines the reinforcement theory. There are positive reinforcement and negative reinforcement. Positive reinforcement is the process of presenting stimuli that can improve the response probability, while negative reinforcement is the process of canceling offensive stimuli to improve the response probability. In the middle of the question, the teacher canceled winter vacation homework's disgusting stimulation because of the excellent grades of students, and the probability of students continuing to study hard in the future may increase, which is a negative reinforcement. Therefore, choose B in this question.