Three sisters are Identical triplets. Who was who ?

Three sisters are identical triplets. The oldest by minutes is Sarah, and Sarah always tells anyone the truth. The next oldest is Sue, and Sue always will tell anyone a lie. Sally is the youngest of the three. She sometimes lies and sometimes tells the truth.

Victor, an old friend of the family's, came over one day and as usual he didn't know who was who, so he asked each of them one question.