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问题 单项选择题

信息系统是由硬件、软件、数据库、远程通信和网络、人员以及过程组成的。其中起主导作用的是______。

A．硬件

B．软件

C．过程

D．人员

答案

参考答案：D

解析： 因为信息系统是由硬件、软件、数据库、远程通信和网络、人员以及过程组成的。其中人员是信息系统中最重要的部分，包括用户和所有管理、运行、编程、维护计算机系统的人员，他们是信息系统的主导。

名词解释

紧张性迷路反射
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单项选择题

A transport layer protocol usually has several responsibilities. One is to create a process-to-processcommunication UDP uses（1）numbers to accomplish this. Another responsibility is to provide controlmechanisms at the transport level, UDP does this task at a very minimal level. There is no flow control mechanismand there is no（2）for received packet. UDP, however, does provide error control to some extent. If UDPdetects an error in the received packet, it will silently drop it.

The transport layer also provides a connection mechanism for the processes. The （3）must be able to sendstreams of data to the transport layer. It is the responsibility of the transport layer at （4） station to make theconnection with the receiver chop the stream into transportable units, number them, and send them one by one. Itis the responsibility of the transport layer at the receiving end to wait until all the different units belonging to thesame process have arrived, check and pass those that are （5）free, and deliver them to the receiving process asa stream.

（2）是（）

A.connection

B.window

C.ackmowledgement

D.destination
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