sun is much bigger than moon.
A:/; /
B:A; a
C:The; the
(Ⅰ)证明:BC⊥AB1;
(Ⅱ)若OC=OA,求二面角A1﹣AC﹣B的余弦值.
两个圆的半径的比是2:1,它们的面积的比就是4:1。
下列对课文《心声》内容理解有误的一项是( )
There is a common belief that movies especially the____(暴力的) movies will have a bad effect on people.