Let's __________ football on Sunday.
A:plays
B:playing
C:play
D:to play
已知A,B均为集合U={1,3,5,7,9}的子集,且A∩B={3},CUB∩A={9},则A=( )
如图,在矩形ABCD中,AD=8,AB=4,点E在AD上,F为AB延长线上一点,将△AEF沿EF翻折,点A恰好与点C重合,则∠AFE的余弦值为 ____.