ACKNOWLEDGEMENTS The authors would like to thank the reviewers for their detailed reviews and constructive comments, which have helped improve the quality of this paper. The research was supported in part by National Basic Research Program of China (973 Program, No. 2013CB329601, No. 2013CB329604), National Natural Science Foundation of China (No.91124002, 61372191, 61472433, 61202362, 11301302), and China Postdoctoral Science Foundation (2013M542560). All opinions, findings, conclusions and recommendations in this paper are those of the authors and do not necessarily reflect the views of the funding agencies.
People's attitudes towards public events or products may change overtime,rather than staying on the same state.Understanding how sentiments change overtime is an interesting and important problem with many application...