Mark the intonation at the end of the polite requests.
Could you phone George, please? (formal polite requests)
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Could you phone George, please?
Could you change the banknote? (formal polite requests)
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-Could you change the banknote?
Can you pass me the salt, please? (Informal polite requests)
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Can you pass me the salt, please?
Can you do the task for me? (Informal polite requests)
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Can you do the task for me?