单项选择题
A.≦3vs/cm2 B.≦4vs/cm2 C.≦5vs/cm2 D.≦6vs/cm2
A.6-8mg/L B.9-10mg/L C.10-11mg/L D.7-12mg/L
A.0.2mmol/L B.0.3mmol/L C.0.4mmol/L D.0.5mmol/L