1. Beijing Key Lab of Information Service Engineering, Beijing Union University, Beijing, P. R. China
2. Beijing Key Lab of Information Service Engineering, Beijing Union University, Beijing, P. R. China, Lab of Computational Linguistics, School of Humanities, Tsinghua University, Beijing, P. R. China, and Center for Psychology and Cognitive Science, Tsinghua University, Beijing, P. R. China
3. Zhengzhou University of Technology, Henan Zhengzhou, P. R. China