Do you know if she's plays the piano?这里plays 是她会弹,还是她弹过没有.

从语法上讲,在这里用plays有问题,应该：Do you know if she is playing the piano?是否正在弹或 .Do you know if she plays the piano?是否会弹 或Do you know if she has played the piano 是否弹过?...