如图3，节点A，B，C，D两两相连，从一个节点沿线段到另一个节点当作1步，若机器人从节点A出发，随机走了3步，则机器人未到达过节点C的概率为
A <img src="https://www.beizhujiaoyu.com/uploads/202208/164066008082551.png" width="16" height="34" /> B <img src="https://www.beizhujiaoyu.com/uploads/202208/164066008531221.png" width="17" height="34" /> C <img src="https://www.beizhujiaoyu.com/uploads/202208/164066008924131.png" width="17" height="34" /> D <img src="https://www.beizhujiaoyu.com/uploads/202208/164066009392131.png" width="17" height="34" /> E <img src="https://www.beizhujiaoyu.com/uploads/202208/164066009713171.png" width="17" height="34" />
