题目选项分析

Mozart himself was a piano virtuoso, and the piano parts of his piano concerti, especially the mature work composed in 1784 and after, have astonishingly difficult finger work, which demands incomparable technique to produce the required elegance and precision.

Mozart himself was a piano virtuoso, and the piano parts of his piano concerti, especially the mature work composed in 1784 and after, have astonishingly difficult finger work, that had demanded incomparable technique to produce the required elegance and precision.