问题 单项选择题

设计批处理多道系统时,首先要考虑的是

A) 灵活性和可适应性
B) 系统效率和吞吐量
C) 交互性和响应时间
D) 实时性和可靠性

答案

参考答案:B

解析: 批处理多道系统能极大地提高计算机系统的工作效率,具体表现为:多道作业并行工作,提高了处理器的利用率;作业调度可以按一定的组合选择装入主存储器的作业,可充分利用计算机系统的资源;作业执行过程中,直接在高速的磁盘上存取信息,从而缩短了作业执行的时间,使单位时间内的处理能力得到提高;作业成批输入,自动选择和控制作业执行,提高了系统的吞吐率。

阅读理解

Read the following passage. Complete the diagram by using the information for the passage. Write NO MORE THAN 3 WORDS for each answer.

Since it was founded a year ago, the babysitting pool has become increasingly popular in the United States. More and more mothers have joined it and have benefited from it. What attracts them most is the idea that you pay your babysitter not in cash, but in paper cards. When you join the babysitting pool, you are given thirty cards, which are worth 30-minute babysitting time each.  For each half an hour while you are gone, the babysitter gets paid one card.

There are rules regulating this service. You should not watch more than three kids at a time including your own. On big holidays, such as Christmas and Thanksgiving, the babysitter should be paid twice as much, which means two cards for every half an hour. When you leave the babysitting pool, you should return all the cards. If you are out of cards, you cannot use money instead. You should have to baby-sit for others to earn enough cards so that you will have them handy when you yourself need a babysitter.

Many mothers think highly of this service. It keeps children in constant touch with one another, and makes life easier for the mothers. Since in most cases, the babysitter is the mother who watches other kids at her own home, it is still possible for her to do her own things while the kids play with each other. In fact most mother babysitters find that their own kids are less of a monster and easier to watch when they are around other playmates. Moreover, since the babysitting pool service does not involve money, it will not be a financial loss to the family.

In the past year, the babysitting pool has helped so many mothers with their work that they all think that it is indeed a good community service worth keeping.

单项选择题