If several fixed navigational lights are visible at the same time, each one may be positiv

The TCP protocolis a (71) layer protocol. Each connection connects two TCPs that may be just one physical network apart or located on opposite sides ofthe globe. In other words, each connection creates a (72) witha length that may be totally different from another path created by another connection. This means that TCP cannot use the same retransmission time for all connections. Selecting afixed retransnussion time for all connections can result in serious consequences. Ifthe retransmission time does not allow enough time for a (73) to reach the destination and an acknowledgment to reach the source, it can result in retransmission of segments that are still on the way. Conversely, if the retransnussion time is longer than necessary for a short path, it may result in delay for the application programs.Even for one single connection, the retransmission time should not be fixed.A connection may be able to send segments and receive (74)faster during nontraffic period than during congested periods. TCP uses the dynamic retransmission time,a transmission time is different for each connection and which may be changed during the same connection. Retransmission time can be made(75) by basing it on the round-trip time (RTT). Several formulas are used for this purpose.

A.physical

B.network

C.transport

D.application@@@SXB@@@A.path

B.window

C.response

D.process@@@SXB@@@A.process

B.segment

C.program

D.user@@@SXB@@@A.connections

B.requests

C.acknowledgments

D.datagrams@@@SXB@@@A.long

B.short

C.fixed

D.dynamic

An analog signal's characteristic quantity representing data may 66). at any instant, any value within a continuous(67). For example, an analog signal may follow continuously the values of another physical quantity representing data.A discrete signal is composed of(68)elements in time, each element having one or more characteristic quantities which can represent data. Examples of characteristic quantities are amplitude, waveform,(69), and position in time. A digital signal is a special case of discrete signals, in which data are represented by a(70)number of well-defined discrete values that one of its characteristic quantities may take in time.

A．acquire

B．collect

C．assume

D．fetch

●The TCP protocolis a (71) layer protocol. Each connection connects two TCPs that may be just one physical network apart or located on opposite sides ofthe globe. In other words, each connection creates a (72) witha length that may be totally different from another path created by another connection. This means that TCP cannot use the same retransmission time for all connections. Selecting afixed retransnussion time for all connections can result in serious consequences. Ifthe retransmission time does not allow enough time for a (73) to reach the destination and an acknowledgment to reach the source, it can result in retransmission of segments that are still on the way. Conversely, if the retransnussion time is longer than necessary for a short path, it may result in delay for the application programs.

Even for one single connection, the retransmission time should not be fixed.A connection may be able to send segments and receive (74)faster during nontraffic period than during congested periods. TCP uses the dynamic retransmission time,a transmission time is different for each connection and which may be changed during the same connection. Retransmission time can be made(75) by basing it on the round-trip time (RTT). Several formulas are used for this purpose.

(71) A.physical

B.network

C.transport

D.application

(72) A.path

B.window

C.response

D.process

(73) A.process

B.segment

C.program

D.user

(74) A.connections

B.requests

C.acknowledgments

D.datagrams

(75) A.long

B.short

C.fixed

D.dynamic

A vessel may exhibit lights other than those prescribed by the Rules as long as the additional lights ______.

A.are not the same color as either side light

B.have a lesser range of visibility than the prescribed lights

C.do not impair the visibility or distinctive character of the prescribed lights

D.All of the above

Ink-jet printer belongs to nonimpact printers in which the characters are formed by projecting particles or droplets of ink on to paper.(71) printer is also a nonimpact printer in which the characters are produced by applying hot elements to heat-sensitive paper directly or by melting ink from a(72) on to plain paper. Electrostatic printer creates an electrostatic latent image, which is then made visible by a toner and transferred and fixed on paper. An electrostatic printer may be used in some instances as a(73). Laser printer creates, by means of a laser beam directed on a(74) surface, a latent image which is then made visible by a toner and transferred and fixed on paper. Magnetographic printer creates, by means of magnetic heads operating on a metallic drum, a latent image which is then made visible by a toner and transferred and fixed on paper. Computer-output-microfilm (COM) printer produces on a photographic film a(75) of each page.

A．Hot

B．Warm

C．Heat

D．Thermal

Many navigational warnings are of a temporary nature，but others remain in force for several months or may be succeeded by ______.

A.Notices to Mariners

B.Sailing Directions

C.List of Lights and Signals

D.Guide to Port Entries

单句理解

听力原文：These time deposits earn higher interest rates, which may be fixed or floating, but no withdrawals are allowed until the term has ended.

(1)

A．Sometimes the interest rates on time deposits are not fixed.

B．People can draw these deposits at any time.

C．The interest rates on time deposits are fixed.

D．The interest rates on time deposits are floating.