Complex sentence: Geezer joined Ozzy Osbourne 1989 and then came back to Black Sabbath on 1991 to reform mark III to left again after the Cross Purposes tour and the "Nativity In Black" affair.
Split into simpler sentences: Geezer joined Ozzy Osbourne 1989 and then came back to Black Sabbath on 1991. He left again after the Cross Purposes tour and the "Nativity In Black" affair.