25×6×45=25×45×6运用的是乘法交换律 .
世界上信徒最多的宗教是( )
I am good at playing basketball,and my brother is good at it.
如果a-1+2-b=0,则1a+6b=____.
(Ⅰ)证明:BC1∥平面A1CD;
(Ⅱ)AA1=AC=CB=2,AB= 22 ,求三棱锥C﹣A1DE的体积.