A.t(n-1) B.t(n) C.χ2(n-1) D.χ2(n)
A.k=2時(shí),f(x)是密度函數(shù) B.k=2x時(shí),f(x)是分布函數(shù) C.k=0時(shí),f(x)是密度函數(shù) D.k=x2時(shí),f(x)是分布函數(shù)