Virginia Yip is Professor at the Department of Linguistics and Modern Languages, The Chinese University of Hong Kong. Stephen Matthews is Professor at the Department of Linguistics at the University of Hong Kong. They are the authors of Cantonese: A Comprehensive Grammar (1994, 2nd edition 2011), The Bilingual Child: Early Development and Language Contact (2007, Cambridge University Press), and co-directors of the Childhood Bilingualism Research Centre.