下列能反映数据分布离散趋势的特征量数是（）
A.相关系数
B.地位量数
C.集中量数
D.差异量数
参考答案：D
圆盘给矿机的优缺点有哪些？
An ______ test is a rough measure of a child's capacity for learning, particularly for learning the kinds of things required at school.
A．proficiency
B．intelligence
C．psychology
D．speed
