呼吸性酸中毒合并代谢性碱中毒的血气改变有（）
A.pH下降
B.HCO3-减少
C.血钾降低
D.血氯降低
E.二氧化碳分压下降
参考答案：C, D
—The accident was really terrible.
—Yes, it was. The young man on the bicycle was too .
A．careless
B．careful
C．carelessly
D．carefully
设函数z=f(x，y) (xy≠0)满足
