题干
—Why are you so depressed?
—I _____ my MP4 player on the bus．
—I _____ my MP4 player on the bus．
A：had lost
B：am lost
C：have lost
D：was lost
答案(点此获取答案解析）
C
，顶点都在一个球面上，则该球的表面积为（ ）