A.n=2[(s/d)(zα+zβ)]2 B.n=3[(s/d)(zα+zβ)]2 C.n=4[(s/d)(zα+zβ)]2 D.n=5[(s/d)(zα+zβ)]2
A.非结构型问卷 B.开放型问卷 C.图画型问卷 D.封闭型问卷