(3)设X1,X2是随机变量,它们的分布函数分别为F1(x),F2(x),为-|||-使 (x)=a(F)_(1)(x)-b(F)_(2)(x) 是某一随机变量的分布函数,在下列给出的各组数-|||-中应取 () .-|||-(A) =dfrac (3)(5), =-dfrac (2)(5); (B) =dfrac (2)(3) =dfrac (2)(3) ;-|||-(C) =-dfrac (1)(2) =dfrac (3)(2) ; (D) =dfrac (1)(2) ,b=3/2,