A、They can both be learnt with complete precision. B、They vary from individual to individual. C、Neither of them is essential to

Most of us have an image of such a normal or standard English in pronunciation, and very commonly in Great Britain this is "Received Pronunciation", which is often associated with the public schools, Oxford, and the BBD. At the same time, it must be remembered that so far as the English-speaking countries are concerned, this "Received Pronunciation" approached the status of a "standard" almost only in England. Educated Scots, Irishmen, Americans, Australians, and others have their own different images of a standard form of English.
    Even in England it is difficult to speak of a standard in pronunciation. Pronunciation is infinitely variable, so that even given the will to adopt a single pronunciation, it would be difficult to achieve. There is no sure way of any two people saying the same word with precisely the same sound. In this respect pronunciation much more closely resembles handwriting than spelling. In spelling, there are absolute distinctions which can be learnt and imitated with complete precision: One can know at once whether a wont is spelt in a standard way or not. But two person’ s handwritings and ciations may both be perfectly intelligible，yet have obvious differences without out being able to say which is“better”or more“standard”．