> Lavoro la mattina.> > Lavoro di mattina.> > Viene a mezzogiorno.>> Bevo caffè alla mattina.Apparently all of them are correct! I am completely confused as to when to use "di", "a" or "in" in front of a time period, and whether to use definite article or not. I did some research online but it seems there is no good summary about preposition in front of a time. Would someone be kind enough to do a summary for me or direct me to a link? Would be appreciated.