c# 音乐播放的问题

WMPLib.WindowsMediaPlayerClass player = new WMPLib.WindowsMediaPlayerClass();
player.URL = @"E:\\ff7sheli.mp3";
player.uiMode = "None";
player.settings.volume = 100;
player.settings.playCount = 1;
player.play();
请问如何判断音乐播放完毕，例如音乐播放完毕后显示一个Messagebox