She_______ Japanese when she was in Japan. Now she can speak it freely.
A:picked out
B:picked up
C:made out
D:made up
如图所示,四棱锥S﹣ABCD的底面ABCD为等腰梯形,AB∥CD,对角线AC与BD交于点O,OA=3,OD=1,CD=2,SO⊥底面ABCD.
求证:SA⊥BD