Acknowledgments

This book is mainly based on my research carried out between 2007 and 2015. Some thoughts behind it can be traced back to my doctoral dissertation submitted to Stanford University, which was completed at 2006. I owe a special debt of gratitude to my doctoral dissertation advisors, Professor Chaofen Sun and Professor Elizabeth Traugott, for their guidance and support throughout my doctoral studies. Over the past several years I have presented some ideas in this book at conferences at New York (2007), Beijing (2009), Kaohsiung (2011), Hawaii (2012), Wuhan (2013), etc. I would like to thank the audiences at these conferences for useful suggestions. I am also grateful to anonymous reviewers, both those commissioned by John Benjamins Publishing Company for their insightful comments on the draft version of the manuscript, and those reviewing my journal papers that form the basis of this book.