A.FN▽≤4.0B.4.0<FN▽< 4.5C.FN▽< 4.5D.FN▽≥8.0
A.FN▽>4.0B.FN▽>3.0C.4.0< FN▽< 4.5D.FN▽>8.0
A.FN▽≥8.0B.FN▽>3.0C.FN▽≥4.0D.FN▽>4.5