经过多年的练习，他终于掌握了这门乐器的技巧。

After years of practice, he achieved complete ___mastery over the instrument.

经过多年的练习，他对钢琴的掌握令人惊叹。

After years of practice, his ___mastery of the piano is truly impressive.

经过几个月的刻苦训练，她终于掌握了这门复杂的乐器。

After months of hard practice, she finally gained ___mastery of this complex instrument.