I am grateful to all the people who have helped me with the preparation of this third edition. A large number of teachers in different countries were kind enough to respond to an enquiry asking how they felt Practical English Usage could be improved: their feedback was extremely helpful, and I am very much in their debt. I am also greatly indebted to David Baker, whose comments and suggestions have added very significantly to the accuracy and clarity of the book, and to Hideo Hibino and Kenji Kashino, who have contributed valuable advice on specific problems. Many other teachers and students - too many to name -have taken the trouble to suggest ways in which particular entries could be improved; their input has benefited the book considerably.
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