问题 单项选择题

在系统转换的过程中,旧系统和新系统并行工作一段时间,再由新系统代替旧系统的策略称为 (3) :在新系统全部正式运行前,一部分一部分地代替旧系统的策略称为 (4)

4()

A.直接转换

B.位置转换

C.分段转换

D.并行转换

答案

参考答案:C

解析:

这道题属于纯概念题,题目中的字句都是从概念中抽出来的,下面我们来看系统转换的一些概念。

新老系统之间的转换有三种方式:直接转换、并行转换和分段转换。

(1)直接转换就是在确定新系统运行无误时,立刻启用新系统,终止老系统运行。这种方式对人员、设备费用很节省。这种方式一般适用于一些处理过程不太复杂,数据不很重要的场合。

(2)并行转换是新老系统并行一段时间,经过一段时间的考验以后,新系统正式替代老系统。对于较复杂的大型系统,它提供了一个与老系统运行结果进行比较的机会,可以对新老两个系统并行工作,消除了尚未认识新系统之前的紧张和不安。在银行、财务和一些企业的核心系统中,这是一种经常使用的转换方式。它的主要特点是安全、可靠,但费用和工作量都很大,因为在相当长的时间内系统要两套班子并行工作。

(3)分段转换又称逐步转换、向导转换、试点过渡法等。这种转换方式实际上是以上两种转换方式的结合。在新系统全部正式运行前,一部分一部分地代替老系统。那些在转换过程中还没有正式运行的部分,可以在一个模拟环境中继续试运行。这种方式既保证了可靠性,又不至于费用太大。但是这种分段转换要求子系统之间有一定的独立性,对系统的设计和实现都有一定的要求,否则就无法实现这种分段转换的设想。

由此可以看出题目所说的“旧系统和新系统并行工作一段时间,再由新系统代替旧系统的策略”是并行转换,而“在新系统全部正式运行前,一部分一部分地代替旧系统的策略”是分段转换。

阅读理解

阅读理解。

     A little boy comes to a new town. His name is Peter. of course, he lives with his mother and father.

His family is very rich.. They have a cook and they have a lot of servants.

     Peter is going to a new school. On the first day his mother says to him, Peter, be modest (谦虚) at your

new school. Don't say we are rich."

     Peter says, "Yes, mother." So Peter goes to school. He meets his new teacher. And he sits down with the

other children. The teacher says," Good morning, children. The first exercise today is a composition (作文).

The topic of the composition is 'my family'." So every child writes a composition. This is Peter's composition.

     "My name is Peter. My family is very poor. My father is very poor. My mother is very poor. The gardener

is very poor. The cook is very poor. And all the other servants are very poor…"

1. Whom does Peter live with?

A. Tom

B. Jack

C. Jim

D. His father and mother

2. Peter's family is _________.

A. very

B. very rich

C. very big

D. very happy

3. His mother tells Peter _________.

A. to study hard at school.

B. not to say their family is very rich.

B. not to say their family is very poor.

D. not to go to school.

4. The teacher asks the children to _________.

A. write a composition

B. do some reading

C. read the text

D. do grammar exercises.

5. Peter _________.

A. does not know how to write a composition.

B. Writes a good composition.

B. Tells his teacher and the other children that his family is very poor.

C. Tells his teacher and the other children that his family is very rich.

单项选择题