问题
填空题
对数据对象施加封锁，可能会引起活锁和死锁问题。预防死锁通常有一次封锁法和 【19】 两种方法。
答案
参考答案：顺序封锁法
解析：
[分析]： 预防死锁有一次封锁法、顺序封锁法。一次封锁法要求每个事务必须一次将所有要使用的数据全部加锁，否则就不能继续执行。顺序封锁法是预先对数据对象规定一个封锁顺序，所有事务都按这个顺序实行封锁。
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对数据对象施加封锁，可能会引起活锁和死锁问题。预防死锁通常有一次封锁法和 【19】 两种方法。
参考答案：顺序封锁法
解析：
[分析]： 预防死锁有一次封锁法、顺序封锁法。一次封锁法要求每个事务必须一次将所有要使用的数据全部加锁，否则就不能继续执行。顺序封锁法是预先对数据对象规定一个封锁顺序，所有事务都按这个顺序实行封锁。
| 阅读短文，选择正确答案。 | ||
| Li Nan was born in Hangzhou, Zhejiang Province. Two years ago, he graduated from medical school at Zhejiang University. Then he volunteered to work with the Go West program. He went to Inner Mongolia Autonomous Region and worked as a doctor. At first, he worked very hard. But he felt lonely because he was a long way from home. Sometimes he felt feel like giving up. But after a short time, he was able to make many new friends. People there were kind and warm-hearted. He began to like the place. Li Nan has just completed his two years of volunteer service and returned home. He said, "I learned a lot. It was a useful experience for me." | ||
| 1. What did Li Nan do in Inner Mongolia? ______ | ||
[ ] | ||
| A. He went to university. B. He worked as a doctor. C. He worked as a teacher. | ||
| 2. How long has Li Nan worked as a volunteer in Inner Mongolia? | ||
[ ] | ||
| A. For four years. B. Since he graduated from Zhejiang University. C. Two years ago. | ||
| 3. Match the words on the left with their definitions on the right. | ||
[ ] | ||
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| 4. What did Li Nan do after he completed his volunteer service? | ||
[ ] | ||
| A. He went back to Zhejiang. B. He stayed in Inner Mongolia. C. He went to university again. | ||
| 5. What did Li Nan think of his volunteer service? | ||
[ ] | ||
| A. It was lonely. B. It was hard. C. It was useful |