A:puzzling; hung
B:puzzled; hung
C:puzzling; hanging
D:puzzled; hanging
如图,在平行四边形ABCD中,对角线AC,BD相交于点O,点E,F分别是边AD,AB的中点,EF交AC于点H,则AHHC的值为____
读“城市形成发展变化图”,完成下列问题.
(make it a rule that...)