Requests in English are usually made in the form of general questions with the help of the modal verbs MAY, CAN, COULD, WILL, WOULD. Requests are pronounced with rising intonation. Adding please to a request makes it more polite. As a rule, polite requests are not asked in the form of negative questions. The modal verbs MAY, COULD, WILL, WOULD are used in making polite requests in speech and writing, in communication with strangers and with people you know. CAN in requests is considered to be less polite than the other modals in this group. CAN is generally used in informal requests, mostly in conversation with friends and family.
Note the use of the pronouns I, you. In requests, MAY is used in the form May I; WILL and WOULD are used in the forms Will you and Would you; COULD and CAN are used in both variants. Use Could you for making a request, and Could I for making a request or for asking for permission. COULD is used in both formal and informal speech and writing. The phrase Would you mind is also very common in making requests or asking for permission, though it is a little more difficult to use than Could you, Could I. Use typical affirmative or negative responses to requests. Do not use negative questions to make a request or ask for permission.