能准确反映代谢性酸碱平衡的指标是
A．PaCO2B．PaO2C．SBD．动脉血pH值E．AB
参考答案：C
若⊙O的半径为5厘米，圆心O到弦AB的距离为3厘米，则弦AB的长为（ ）厘米。
—What do we need to buy?
—We need _____.[ ]
A. two carton of milk
B. two cartons of milks
C. two cartons of milk
D. two carton of milks
