关于对称分布资料，理论算术均数和中位数的大小关系是（）

A.相等

B.算术均数大于中位数

C.算术均数小于中位数

D.不能确定谁大谁小

E.两者之间无可比性

When evacuating a seaman by helicopter lift，which course should the ship take?（）

A.Downwind so that the apparent wind is close to nil

B.A course that will keep a free flow of air，clear of smoke，over the hoist area

C.A course that will have the hoist area in the lee of the superstructure

D.With the wind dead ahead because the helicopter is more maneuverable when going into the wind