A:①②
B:②③
C:③④
D:①④
When I went shopping yesterday, I ____ my motorbike ____ .
如图,在平行四边形ABCD中,对角线AC,BD相交于点 O,若BD,AC的和为18 cm,CD:DA=2:3,△AOB的周长为13cm,那么BC的长是( )