A:3
B:2 3
C:2
D:3 2
Last Sunday, a group of pupils talked happily a loud voice as they went to the countryside bike.
如图,在矩形ABCD中,对角线AC、BD相交于点O,点E、F分别是AO、AD的中点,若AB=6cm,BC=8cm,则△AEF的周长为( )
Can you play yo-yo? ____
宋朝居当时世界首位的手工业部门是( )