船速度为v1 流水速度为v2 AB距离为S得 S/(v1+v2)=2 S/(v1-v2)=3整理得 2(v1+v2)=3(v1-v2) 5v2=v1现在题目求的是 S/v2把5v2=v1 代入S/(v1+v2)=2得 S/6v2=2 S/v2=12答案就是12h