Since Web 2.0 emerges, users became very active in attending Web forum and Q&A Community. For the community about technology, engineering and science, it is likely that most of the professionals follow the same general path to study specific knowledge and this path would be between topics from basic one to specific one or from topic about old technology to a topic about new technology. Our work aims to find this general conditional relationship between topics by using Bayesian Network model and then use this model to suggest the reasonable topics for professionals to further study.