有关黄河的特点叙述正确的是 ( )
After the education reform(改革) in Jiangsu Province, the pupils have_______ time to relax and _______ homework to do.
如图,菱形ABCD的对角线AC、BD相交于点O,AC=8,BD=6,过点O作OH⊥AB,垂足为H,则点O到边AB的距离OH等于( )