铁路技规规定铁路哪些地方应装设无线电话？
参考答案：铁路各调度区段应装设列车无线调度电话，在编组区段站，区段站，根椐需要装设场无线电话。
He's succeeded in many scientific fields. However, his wife is an ordinary woman, _____?[ ]
A. is she
B. isn't she
C. doesn't he
D. hasn't he
前序遍历和中序遍历结果相同的二叉树为( )。
A．根结点无左孩子的二叉树
B．根结点无右孩子的二叉树
C．所有结点只有左子树的二叉树
D．所有结点只有右子树的二叉树
