“一个事务中的诸操作要么都做，要么都不做”，这一性质是指事务的（）
A．原子性
B．一致性
C． 隔离性
D．持久性
参考答案：A
解析：
原子性：一个事务是一个不可分割的工作单位，事务中包括的诸操作要么都做，要么都不做。
一致性：事务必须是使数据库从一个一致性状态变到另一个一致性状态。一致性与原子性是密切相关的。
隔离性：一个事务的执行不能被其他事务干扰。即一个事务内部的操作及使用的数据对并发的其他事务是隔离的，并发执行的各个事务之间不能互相干扰。
持久性：持续性也称永久性，指一个事务一旦提交，它对数据库中数据的改变就应该是永久性的。
Everyone needs a break, and vacations are not meant for serious study. Instead, they’re a great way to take a break and enjoy a good book. The Spring Festival is coming up so this is the perfect time to discuss some great English language literature to take on a long train journey or while you’re hanging out with the family. Before getting into the recommendations, we need to determine your English reading comprehension level so you don’t pick a book which is so challenging that it’s stressful or so simple that it’s boring. If you’re at the beginner level, there are two options: reading a children’s book or reading a book that you’ve read in Chinese translation. This will help you get over any unfamiliar words or phrases, since you’re already familiar with the story. If you’re at the intermediate level, popular books like pop fiction, mysteries and thrillers are good options, as they’ll be guaranteed page turners and that will increase the possibility of your getting all the way through the book. For advanced readers, science fiction, classic works of literature or contemporary prize winners （Booker, Nobel, Pulitzer） are good options. The most important thing is to pick a book that you’re really interested in. When I pick up a new book in Chinese, the first few chapters are always really hard to get through, as I have to get accustomed to the way the individual author uses the language. But after the first few chapters, things get a lot easier, especially if I get involved in the story. Some of my favorite Chinese-language eye candy are books that are series like Brothers by Yu Hua or The Dancer by Hai Yan. I like them because there’s always a lot of action and story development to keep me involved, which helps me make it through those first few chapters. Another great way to keep yourself motivated over the holiday is to find a friend who’s interested in reading the same book. You can make goals that you both want to achieve and discuss plot lines or vocabulary issues with each other by SMS or e-mail. I’m currently doing that with my friend Laura. We’ve been doing this since we were classmates in Chinese at college. Some quick recommendations: Harry Potter, start with the first book and go on from there; the Narnia series; anything by US writer Michael Crichton or British writer Agatha Christie; and if you like horror, US writer Stephen King is always unusual and fun. But really you should just find a topic or author that you’re interested in, and the rest will go from there. Happy reading! －from 21st Century （January 21, 2009）
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