c & d (=/ gender ) 1 oldest(father) & d (=/ gender ) 2 youngest & b (=/gender) 3 age c > b 4 father = oldest 5 youngest (=/ a) 6
sub. 5 into 2 d = female so c = male ======== prove that youngest one isnt a so a = father or mother ======== 无脑推理环节(从已确定的资料) a= 凶手(父/母) b=被害 c=帮凶(已确定为男性) d=目击