"He is playing the piano" 是表示 "他在弹钢琴" 的常用说法。

来源：这是一种常用的英语说法，用于描述某人在弹奏钢琴。

英文例句及中文翻译：

He is playing a beautiful piece on the piano. 他在钢琴上弹奏一首美妙的曲子。
She has been playing the piano since she was a child. 她从小就开始弹钢琴。
He is an accomppshed pianist who enjoys playing classical pieces. 他是一位高超的钢琴家，喜欢弹奏古典曲目。