It's important______the piano well.
A:of him to play
B:for him to play
C:of him playing
D:for him playing
化合物A在一定条件下发生分解反应,反应物浓度随反应时间的变化如图所示.则化合物A在4~8min间的平均反应速率为( )
阅读下面一幅新闻图片,用简洁的语言概述图片内容,并谈谈受助者为什么会有这样的反应。