单项选择题
A.500mg/L，＞30min B.250mg/L，＞30min C.500mg/L，≥30min D.250mg/L，≥30min
A.消毒；2 B.清洁；2 C.清洁；1 D.消毒；1
A.2遍，≥5cm×5cm B.1遍，≥3cm×3cm C.1遍，≥5cm×5cm D.2遍，≥3cm×3cm