矩形ABCD中,AB= 4,BC=3,沿AC将矩形ABCD折成一个直二面角B-AC-D,则四面体ABCD的外接球的体积为( )
A:125π6
B:125π12
C:125π9
D:125π3
属于纵贯南北美洲西部山系的山脉是 ( )
--- Is her sister a teacher or a student?
--- .