The number of speakers of English in Shakespeare’s time is estimated (估计) to have been about five million. Today it is estimated that some 260 million people speak it as a native language, mainly in the United States, Canada, Great Britain, Ireland, South Africa, Australia and New Zealand. In addition to the standard varieties of English found in these areas, there are a great many regional and social varieties of the language as well as various levels of usage that are employed both in its spoken and written forms.<BR> In fact, it is impossible to estimate the number of people in the world who have acquired an adequate (足够的) working knowledge of English in addition to their own languages. The purpose for English learning and the situations in which such learning takes place are so varied that it is difficult to explain and still more difficult to judge what forms an adequate working knowledge for each situation.<BR> The main reason for the widespread dema