The（71)has several major components, including the system kernel, a memory management syst

system, the file system manager, device drivers, and the system libraries.

（71）

A. application

B. information system

C. operating system

D. information processing

the best answer and write down on the answer sheet．

Spread spectrum simply means that data is sent in（1 ）pieces over a number of the discrete frequencies available for use at any time in the specified range．Devices using（2 ） spread spectrum(DSSS)communicate by splitting each（3 ）of data into several parts and sending them concurrently on different（4 ），DSSS uses a lot of the available（5 ），about 22 megahertz(MHz)．

第71题：文中（1 ）处正确的答案是（）。

A．small

B．high

C．low

D．long

like RIP, treats eaCh network as equals.The (71) of passing through eaCh network is the same;it is one (72) Count.So if a paCket passes through 10 network to reaCh the Destination, the total Cost is 10 hop Counts.Other protoCols, suCh as OSPF, allow the aDministrator to assign a Cost for passing through a network BaseD on the type of serviCe requireD.A (73) through a network Can have Different Costs(metriCs).For example, if maximum (74) is the DesireD type of serviCe, a satellite link has a lower metriC than a fiBer-optiC line.On the other hanD, if minimum (75) is the DesireD type of serviCe, a fiBer-optiC line has a lower metriC than a satellite line.OSPF allow eaCh router to have several routing taBle BaseD on the requireD type of serviCe.

（71）

A．numBer

B．ConneCtion

C．Diagram

D．Cost

cess (program-to-program) communication; TCP uses port (71) to accomplish this. Another responsibility of a transport layer protocol is to create a (72) and error-control mechanism at the transport level. TCP uses a sliding (73) protocol to achieve flow control. It uses the acknowledgment packet, time-out, and retransmission to achieve (74) control. The transport layer is also responsible for providing a connection mechanism for the application program. The application program sends (75) of data to the transport layer. It is the responsibility of the transport layer at the sending station to make a connection with the receiver.

（71）

A．numbers

B．connections

C．diagrams

D．resources

rocess (program-to-program) communication; TCP uses port （71） to accomplish this. Another responsibility of a transport layer protocol is to create a （72） and error-control mechanism at the transport level. TCP uses a sliding （73） protocol to achieve flow control. It uses the acknowledgment packet, time-out, and retransmission to achieve （74） control. The transport layer is also responsible for providing a connection mechanism for the application program. The application program sends （75） of data to the transport layer. It is the responsibility of the transport layer at the sending station to make a connection with the receiver.

（71）

A. numbers

B. connections

C. diagrams

D. resources

（72）

A. procedure

B. function

C. route

D. flow

（73）

A. path

B. window

C. frame

D. diagram

（74）

A. packet

B. time

C. error

D. phase

（75）

A. ports

B. streams

C. packets

D. cells

ess-to-process communication; UDP uses （71） numbers to accomplish this. Another responsibility is to provide control mechanisms at the transport level. UDP does this task at a very minimal level. There is no flow control mechanism and there is no （72） for received packet. UDP,however, does provide error control to some extent. If UDP detects an error in the received packet, it will silently drop it．

The transport layer also provides a connection mechanism for the processes. The （73） must be able to send streams of data to the transport layer. It is the responsibility of the transport layer at （74） station to make the connection with the receiver, chop the stream into transportable units,number them, and send them one by one. It is the responsibility of the transport layer at the receiving end to wait until all the different units belonging to the same process have arrived, check and pass those that are （75） free, and deliver them to the receiving process as a stream.

（71）A．hop B．port C．route D．packet

（72）A．connection B．window C．acknowledgement D．destination

（73）A．jobs B．processes C．programs D．users

（74）A．sending B．routing C．switching D．receiving

（75）A．call B．state C．cost D．error

l, like RIP, treats each network as equals. The （71） of passing through each network is the same; it is one （72） count. So if a packet passes through 10 network to reach the destination, the total cost is 10 hop counts. Other protocols, such as OSPF, allow the administrator to assign a cost for passing through a network based on the type of service required. A （73） through a network can have different costs (metrics). For example, if maximum （74） is the desired type of service, a satellite link has a lower metric than a fiber-optic line. On the other hand, if minimum （75） is the desired type of service, a fiber-optic line has a lower metric than a satellite line. OSPF allow each router to have several routing table based on the required type of service.

（71）

A. number

B. connection

C. diagram

D. cost

（72）

A. process

B. hop

C. route

D. flow

（73）

A. flow

B. window

C. route

D. cost

（74）

A. packet

B. throughput

C. error

D. number

（75）

A. delay

B. stream

C. packet

D. cost

听力原文：W: How are you getting on with your experiment？

M: In spite of my continuous failure, I have already made some progress.

What can we learn about the man's enperiment ？

A．It is going on well.

B．It has failed several times.

C．It will soon be finished.

D．It may have to be stopped.

●In general,atypical (71) model is composed of several phases, such as requirements analysis phase, generaUdetailed design phase, implementation phase, system acceptance testing phase.

(71)

A. waterfall

B.incremental

C.spiral

D.prototyping

One use of networks is to let several computers share(71)such as file systems, printers, and tape drives.

A．CPU

B．memory

C．resources

D．data