We use please to make a request more polite.
- Would you move a bit, please?
- Could you open the window, please?
- ‘Would you like some help?’ ‘Yes, please.’
Please do is a rather formal answer to a request for permission.
- ‘Do you mind if I open the window?’ ‘Please do.’
Situations where please is not used
We do not use please to ask people what they have said.
- ‘I have got a bit of a headache.’ ‘I beg your pardon?’ (NOT … Please?)
- ‘John is on the phone.’ ‘Sorry?’ (NOT …Please?)
Please is not used as an answer to Thank you.
- ‘Thanks a lot.’ ‘That’s OK.’ (NOT … ‘Please.’)