以下关于静脉留置针的封管技术，叙述正确的是：
A.封管液一般为10～100IU/ml浓度的肝素稀释液
B．肝素稀释液封管剂量为2～5ml/次
C.有出血倾向者，封管可用0.9％氯化钠溶液
D.用O.9％氯化钠溶液封管时，每次剂量为5～10m1
E．采用正压封管法
The intercept in the multiple regression model
A. should be excluded if one explanatory variable has negative values.
B. determines the height of the regression line.
C. should be excluded because the population regression function does not go through the origin.
D. is statistically significant if it is larger than 1.96.
The term “linear” in a multiple linear regression model means that the equation is linear in parameters.
A. 对
B. 错
中心静脉压测定的正常值：( )
A. 5-12cmH2O
B. 5-14cmH2O
C. 3-12cmH2O
D. 2-12cmH2O
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