首页
普通专升本
成人高考
学位英语
在线刷题
最近学习
最近学习课程
最强大脑 · 3天挑战极限记...
副标题副标题副标题副
最强大脑 · 3天挑战极限记...
副标题副标题副标题副
您现在位置：
模拟考场
>
湖北自学考试
>
公共课
>
管理系统中计算机应用
>
浏览试题
[单选题]
15．概括信息系统的基本结构，对信息系统的主要功能做出约定的数据流程图是
A
A．背景图 B．项层数据流程图 C．内外关系图 D．低层次数据流程图
收藏
查看答案
参考答案
试题答案：
B
答案解释：
相关题目
虽然二范式的关系已经比原来一范式的关系优越了许多，但仍存在插入异常、删除异常和冗余太大，之所以产生这些问题是由于存在 （ ）
26．下列选项中，不属于可靠性技术的是
以下有关C/S模式说法错误的是 （ ）
27．改正在系统开发阶段遗留的而系统测试阶段未能发现的错误称为
33.
下列选项中，不是运行管理的基本内容的是 （ ）
物流
23．系统开发过程中，首先要完成
热门试题
1.
22.在结构化程序设计中，模块间的耦合性低的好处是
2.
24．垄断产生的物质条件和基础是（ ）
3.
23.儿童最大利益原则
4.
（ ）是把年龄和知识水平相同或相近的学生，按照班级定额合理分配，组成平行班，以便实施教育和教学活动。
5.
3. Friction is a force which opposes motion. Much of the energy supplied to a complicated machine with many moving parts is wasted in overcoming this opposition. The energy is converted into useless heat. The amount thus lost can be considerably reduced and the life of the machine prolonged by careful lubrication. This reduction improves the efficiency of the machine. Another way in which friction is reduced is to substitute roller or ball bearings for the earlier type of bearing, in which the surfaces in contact move by sliding. Bearings of these later types are used very extensively in many kinds of modern machinery.It must not be assumed, however, that friction is always a disadvantage. In many instances it is highly important. Belts are often used in conveying power from one machine to another. In the absence of friction, this could not be done. The driving wheel would not run the belt, neither would the belt run the wheel to driver. Without friction, then, belted machinery could not be used. Again in the case of all motor vehicles, friction is essential in the operation of the brake. Were there no friction, there could be no brake. But even this illustration does not give an adequate picture of the importance of friction. The vehicle could not even be started if it were not for the friction exerted between the tires and the road. Nails hold in wood, and screws hold in either wood or metal by reason of friction, without which they would be useless. Walking is difficult enough on an icy pavement, but it would be wholly impossible if there were no friction at all between the shoe and the pavement.(5分)3.1 Friction arises when____.(1分)A. an opposing force of motion exists B. the energy is wastedC. everything is motionlessD. a complicated machine is supplied with energy
热门试卷
成人高考专升本《政治》模拟试卷
去做题
已有3411做题
2020年湖北成人高考专升本政治模拟试题三
去做题
已有2205做题
成人高考专升本政治考试模拟试题及答案(1)
去做题
已有1893做题
湖北成考专升本政治真题（2021年）
去做题
已有1331做题
成人高考高起点语文考试高分突破试题及答案四
去做题
已有1190做题
