在树T中，结点x的度为k(k＞1)，结点y是结点x最右边一个子女，在与树T对应的二叉树中，也列结论成立的是
A．y一定是x在左子女
B．y一定是x的右子女
C．y的左子树一定是空二叉树
D．y的右子树一定是空二叉树
参考答案：D
解析： 用二叉树表示一棵树的方法可以概括为“左子女-右兄弟”表示法，也就是：在树中，如果结点y是结点x的第1个子女，那么在二叉树中y就是x的左子女；如果y是x的右兄弟，则在二叉树中y将是x的右子女。根据这一规则，本题中y是x的最右边一个子女，所以在它的右边没有兄弟结点，所以它就没有右子女。也就是说它的右子树为空。
阅读理解。 |
| Uncle Li and Uncle Wang are good friends. They live next to each other and their farms are both at the foot of the mountain. So they can help each other. But neither of them likes to use his head. They're both poor though they work hard. Most villagers have built new houses, but they still live in the low and broken houses. They never find out why.Once Uncle Li went to town to buy some medicine for his wife. In the town he heard the apples in a city were expensive. He told Uncle Wang about it as soon as he went back. They decided to carry some apples to the city. They borrowed some money from their friends and bought nearly 1,000 kilograms of apples in the villages and carried them to the city on a tractor. Bad luck! A lot of apples have already been carried there when they arrived. A few days later they had to sell them at a low price (价格).They felt unhappy and returned to their village. "I can't understand why we sustained (蒙受) losses in business while others always profit (盈利)" Uncle Li asked one day. "The tractor was too small" Uncle Wang said without thinking. "We'll carry more apples on a truck next time!" "I agree!" said Uncle Li. "How foolish we were!" |
| 1. Uncle Li and Uncle Wang live in the low and broken houses because ______. |
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| A. they hope to save money B. they're both poor C. their farms are at the foot of the mountain D. they're not far from their farms |
| 2. The two farmers carried the apples to the city to ______. |
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| A. make a journey B. visit some places of interest C. meet their friends D. make a profit |
| 3. The tow farmers had to sell their apples at a low price because ______. |
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| A. theirs weren't as good as the others' B. theirs were much less than the others' C. a lot of apples had been already carried to the city D. they forgot to carry them on a truck |
| 4. Uncle Li and Uncle Wang were unhappy because ______. |
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| A. they had sustained losses in business B. they had lost some money in the city C. something was wrong with the tractor D. other people profited in the city |
| 5. Which of the following is true? |
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| A. The two farmers found out why they were poor. B. The two farmers will soon get rich. C. Neither of the farmers is clever. D. The two farmers decided to buy a truck. |