(1) Requests :
- Can (or could) you wait for a moment, please?
- Excuse me, could you tell me how to get to the railway station?
- Could ( or would) you lend me some money until next week?
(2) Asking for things:
- Can I have these postcards, please?
- Yes of course, you can have them.
- Could I have the salt, please?
(3) Asking for and giving permission:
- Could I use your phone? Yes of course.
- May I come in? Yes, please do.
- You can use my phone. (OR) You may use my phone.( Note:- ‘May’ is formal and less usual than ‘ can ‘ or ‘ could ‘)
(4) Offering to do things:
- Can I get you a cup of coffee?
- Can I help you?
- No, thank you. I can manage.
- ( You can also use I will …..to offer to do things.) You look tired. I will get you a cup of coffee.