题目12.已知 (A)=P(B)=P(C)=dfrac (1)(5) , P(AC)=0 , (AB)=P(BC)=dfrac (1)(10), 则事件A,-|||-B,C全不发生的概率为 ()-|||-A.0.2 B.0.4 C.0.3 D.0.5题目解答答案