英语翻译The frequent change of English teaching textbooks is to

The frequency of changing English teaching textbooks is to enlarge learners' vocabulary andimprove their grammatical competece。Textbook has a vital and positive part to play in the everyday job of teaching and learning English,and that the importance of the textbook becomes even greater in periods of change。Finally,we consider the implications of a more informed and positive view of the role of the textbook,emphasizing,in particular,the need to see textbook creation and teacher education as complementary and mutually beneficial aspects of professional development。