Jordan is the fourth of the five children, ________two brothers and two               sisters.[ ]

A. have; older    

B. having; older

C. has; elder    

D. having; elder

变异系数CV的数值（）。

A.一定大于1

B.一定小于1

C.可大于1，也可小于1

D.一定比标准差小

E.一定比均数小