第16题: [单项选择]一棵非空的二叉树的先序遍历序列与后序遍历序列正好相反,则该二叉树一定满足( )。 A. 所有的结点均无左孩子 B. 所有的结点均无右孩子 C. 只有一个叶子结点 D. 是任意一棵二叉树 参考答案:C 答案解析:前序序列是“根左右”,后序序列是“左右根”,若要这两个序列相反,只有单支树,所以本题的A和B均对,单支树的特点是只有一个叶子结点,故C是最合适的,选C。A或B都不全。
第23题: [单项选择]Questions 11 to 18 are based on the conversation you have just heard. A. His errors were mainly in the reading part. B. It wasn’t very challenging to him. C. It was more difficult than he had expected. D. He made very few grammatical mistakes in his test. 参考答案:C 答案解析:[听力原文] W: How was the English exam you took yesterday M: Not as easy as I expected, I did fai