Hi,<br/><br/>Why is "COULD" used in the following dialogue?<br/><br/>A: Oh, Donald I have got a great idea.<br/><br/>B: What<br/><br/>A: Why do not you come with me tomorrow to the audition? You COULD be my partner and support my elbows!<br/><br/>B: Audition, me ,no.<br/><br/>A: Oh, Donald please.<br/><br/>Is this show to POSSIBILITY, SUGGESTION or POLITE FORM OF CAN?<br/><br/>Thank you