H. use can or could to ask people to do things. (e.g. Can you wait a moment, please? Or Could you wait a moment, please?)
a. we say Do you think you could ~? (not can) (e.g. Do you think you could lend me some money until next week?)
b. also use will and would to ask people to do things (but can/ could are more usual) (e.g. Ann, will you do me a favour?)

H1. To ask for something, we use Can I have ~ or Could I have ~? (e.g. in a shop: Can I have these postcards, please?)
a. may I have ~ ? Is also possible (e.g. May I have these postcards, please?)

H2. To ask to do something, we use can, could or may. (e.g. on the phone: Hello, can I speak to Bob, please?)
a. May is more formal than can or could.
b. To ask to do something, you can also say Do you mind if I ~ ? Or It is all right/ It is OK if I ~? (e.g. Do you mind if I use your phone? Sure. Go ahead)

H3. To offer to do something, you can use can I ~? (e.g. Can I get you a cup of coffee? Yes, please.)
a. I’d like ~ is a polite word of saying what you want. (e.g. (at a tourist office) I’d like some information about hotels, please.)