Zhang Delu is Professor of Linguistics at the School of Foreign Languages, Tongji University, China. His research areas include systemic functional linguistics, discourse analysis and multimodal discourse analysis. He has authored and co-authored 25 books. Liu Rushan is Professor of Linguistics at the School of Foreign Languages, Ocean University of China. His research areas include sociolinguistics, second language acquisition and discourse analysis. He has published more than 30 papers in some key journals.