为确保数据能完整地从终端微机传送到主机，且不存在任何外加的数据，下面哪一项计算机控制程序将最有效
A．采用校验位技术，以确保只有经批准的零部件代码能添加到数据库中。
B．采用批控制总数校验，包括控制每批的数量与金额总数和杂项总数。
C．设置密码，确保只有经批准的人才能将数据发送到主机。
D．设置字段编辑控制，由计算机自动检查每个字段的字母/数字的完整性。
参考答案：B
解析： A．不正确，采用校验位技术能够检查数据的正确性，但对于数据丢失等情况就无能为力了。
B．正确。批控制总数校验可以检查出绝大部分数据错误，如数据错位、丢失、重发等。杂项总数校验则可以进一步提高错误检测率，对一些批总数控制无法发现的错误(如多项金额同时发生错误，但总数不变的情况)，杂项总数控制也能发现。
C．不正确，设置密码只能保证输入数据的人是经授权的，但不能防止该人员输入数据发生错误。
D．不正确，字段编辑控制只能控制输入的是合理的字段，无法控制输入数据的数量和准确性、完整性。
| 阅读理解。 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Girls wore grey skirts and white shirts, boys wore grey trousers, and everyone wore the school tie. Some of Sam's lessons were a bit strange for me. We were reading Shakespeare in the English lesson, and there were quite some old words like "thou" and "thee" to mean "you". In history we studied 20th Century China. It was strange hearing a foreign side of history-and hearing English people trying to say all our Chinese names! Classes were also a lot more relaxed than in China. Teachers were called "sir" or "miss", everyone shouted answers and raised their hands in classes. It was more like a debate than a class. A bell rang at the end of each lesson and everyone jumped up to go to the next class. At break we bought potato chips and cookies in the dining room. Lunch was later than in China-at 1 o'clock. We had big plates of pie with carrots. For dessert there was hot sweet rice called rice pudding. It was good that I'd had an excellent lunch, because at Sam's school Monday afternoons are taken up with sports. I played my first game of netball-a bit like basketball, but with some differences. Luckily I'd had a quick look in the rule book before I tried to join in the game.
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| 1. Paragraph 2 shows that _______. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| A. they wear uniforms in Sam's school B. lessons are different between schools in China and the UK C. there is a break of 30 minutes every day in the school D. sports take up much time in Sam's school | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 2. The underlined word debate in Paragraph 4 means ___________. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| A. fight B. exam C. discussion D. suggestion | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 3. What do they have for lunch at Sam's school? | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| A. Pie and hot sweet rice. B. Potato chips. C. Cookies. D. Carrots. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 4. How many hours do they have for foreign language study? | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| A. 4 hours. B. 2 hours. C. 3 hours. D. 6 hours. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 5. What's the best title for the passage? | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| A. Relaxed Classes in the UK B. Clothes, Food and Sports in a UK School C. Strange Lessons in Sam's School D. A Day in Sam's School |