teachers which of the followings is the most colloquial aone and the most formal one?<br/><br/>1) can I sign instead of him?<br/><br/>2) Is it possible that I sign instead of him(by the way, is it awkward to use 'is it possible' phrase)?<br/><br/>3) can I make a signature instead of him? <br/><br/>4) can I do the signing for him?<br/><br/><br/>thank you!