A:2.6 0.9 1.2
B:2.5 0.8 1.3
C:2.5 0.9 1.4
D:2.5 0.9 1.3
用黑板擦在黑板上擦动时,第一次沿圆周擦动,第二次沿直线擦动,前后两次的摩擦分别是( )
—What did you do last weekend?
—I ______ to the countryside with my family.
如图,矩形ABCD的对角线AC和BD相交于点O,过点O的直线分别交AD和BC于点E、F,AB=2,BC=3,则图中阴影部分的面积为( )