Original sentence: Due to her excellent singing technique and the ease with which she could master different registers, at the time of her prime (60's and 70's), she was able to sing simultaneously both alto, mezzo-soprano and soprano roles, either lyric, dramatic or coloratura.The marriage ended in divorce
Edited sentence: According to Ivo Vinco, the relationship between Callas and Cossotto was friendly and it was Callas who insisted on inviting Cossotto to sing Adalgisa.Due to her perfect singing technique, and the ease with which she could master different registers, at the time of her prime (60's and 70's) she was able to sing simultaneously both alto, mezzo-soprano and soprano roles, either lyric, dramatic or coloratura.Some rumors tell that Cossotto abused Callas intentionally by over-singing her and holding high notes longer when the latter's voice (by that time - 1965) was in poor form.This is not necessarily true.finally, the divorced