心理活动动力特征不包括（）
A.强度
B.速度
C.稳定性
D.平衡性
E.指向性
参考答案：D
He spends as much time as he can _______ English every day. [ ]
A. to practice speaking
B. to practice to speak
C. practice to speak
D. practicing speaking
当血钙低于哪个数值时可引起手足搐搦
A．血总钙 ＜2.2～2.35mmol/L
B．血总钙 ＜2.0～2.45mmol/L
C．血离子钙 ＜1.88～2.2mmol/L
D．血离子钙 ＜1.75～1.88mmol/L
E．血总钙 ＜1.75～1.88mmol/L
