A、Al2O3>16%,F(xiàn)e2O3<0.3% B、Al2O3>16%,F(xiàn)e2O3<0.4% C、Al2O3>25%,F(xiàn)e2O3<0.4% D、Al2O3>25%,F(xiàn)e2O3<0.3%