设随机变量X~N(0,1),随机变量Y~N(1,4),且X与Y相互独立,则 A.P(X+Y<=0)=P(X+Y>=0)B.P(X+Y<=1)=P(X+Y>=1) C.P(X-Y<=0)=P(X-Y>=0)D.P(X-Y<=1)=P(X-Y>=1