题目

I learned to play on a piano purchased at Grinnell Brothers in Detroit.My brothers and sisters were taking lessons and I   41_ to play，too.“You’re  42_  young，” I heard over and over.But when I began playing my sister’s  43_  by heart from hearing her practice，they  44_  me begin.I was four.What joy and comfort I found at those  45_  .If I had a rough day at school，I played ragtime hard and loud  46_  my frustration(挫折) was gone，then I calmed myself with Mozart until I was   47_   to face the world.The day I lost my first child，and my dad was 组成星球的物质是靠引力吸引在一起的，这样的星球有一个最大的自转速率．如果超过了该速率，星球的万有引力将不足以维持其赤道附近的物体做圆周运动．由此能得到半径为R、密度为ρ、质量为M且均匀分布的星球的最小自转周期T．下列表达式中正确的是 A．T＝2π B．T＝2π C．T＝ D．T＝