A.50s B.30s C.60s D.15s
A.50mL;(400±40)r/min;8min B.30mL;(600±60)r/min;8min C.30mL;(600±40)r/min;10min D.30mL;(400±40)r/min;8min
A.15% B.5% C.20% D.10%