输血时出现溶血反应,其典型症状是()
A.四肢麻木,腰背酸痛
B.寒战、发热
C.手足抽搐,心悸
D.荨麻疹,胸闷
E.呼吸困难,咯粉红色泡沫样血痰
参考答案:A
Father often tells me too much time on computer games. [ ]
A. don't spend
B. not spend
C. not to spend
D. not spending
用最小二乘法确定直线回归方程的原则是()
A.各观测点距直线的垂直距离相等
B.各观测点距直线的纵向距离平方和最小
C.各观测点距直线的纵向距离相等
D.各观测点距直线的垂直距离平方和最小
E.各观测点距直线的纵向距离最小