已知三棱锥D﹣ABC的顶点都在球O的球面上,AB=4,BC=3,∠ABC=90 °,AD=12,且
DA⊥平面ABC,则球O的半径等于( )
--Tom is such a stupid student that he had failed in every exam.
---Sorry, I won’t agree. He is ________ than stupid.
A.lazier
B.no lazier
C.more lazy
D.lazier rather
一个圆锥体铁块,体积是32立方厘米,底面积是12平方厘米,那么圆锥体的高度是( )厘米。这个铁块的体积比与它等底等高的圆柱体铁块的体积少( )立方厘米。