Why do Britons, Americans, Canadians and Australians all speak English

Why do Britons, Americans, Canadians and Australians all speak English

Britain is the birthplace of English. Many Americans are British immigrants. Canada and Australia are former British colonies. Most of them are descendants of British people, so most of them speak English

Is the English spoken by the British pure or by the Americans pure?

What are the differences between the British and the Americans?
Both countries speak the same language. Although American English is used in America, it's just a little different in accent
Are the British gentlemanly?
What do you think?

Authentic Oxford English has become the world's language. Many people like British English because of its auditory effect. British people have heavy articulation, full vowels, large undulating tone, feel like tango, step by step, and have a large range of actions. American English has light articulation, weak vowels, and small rise and fall. American English, which is "uncivilized English", is more suitable for most people
The Americans are cheerful, confident, brave and lively, while the traditional British are introverted, indifferent, polite, honest and reliable, and have a sense of national superiority. The British and Americans are not convinced with each other. The British say that the Americans have no history, and the Americans say that the British do not understand the future, Unconsciously, words and deeds also reflect the differences between British and American cultures