题目内容
（请给出正确答案）
A.broadcast
B.multicast
C.unicast
D.global
参考答案
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更多“A sender transmits one copy of the packet that contains the ______ address and all computers receive…”相关的问题
A、RS-232-C specifies that a sender transmits a start bit before transmitting the bits of a character, and a stop bit is appended to each character.
B、When it finishes transmission, the sender leaves the wire with a positive voltage until another character is ready for transmission.
C、RS-232-C uses voltage ranging from -5 volts to +5 volts.
D、Negative voltage corresponds to logical 0, while positive voltage corresponds to logical 1.
The usual way to ensure reliable delivery is to provide the (71) with some feedback about what is happening at the other end of the line. Typically, the protocol calls for the receiver to send back special (72) flame bearing positive or negative (73) about the incoming frames. If the sender receives a positive acknowledgement about a frame, it knows the frame. has arrived safely. On the other hand, a negative acknowledgement means that' something has gone wrong, and the frame. must be transmitted again.
An additional complication comes from the possibility that hardware troubles may cause a flame to (74) completely. In this case, the receiver will not react at all, since it has no any reason to react. It should be clear that a protocol in which the sender transmits a frame. and then waits for an acknowledgement, positive or negative, will hang forever if a frame. is ever lost due to, for example, (75) hardware.
A．receiver
B．controller
C．sender
D．customer
frame. to （74） completely. In this case, the receiver will not react at all, since it has no any reason to react. It should be clear that a protocol in which the sender transmits a frame. and then waits for an acknowledgement, positive or negative, will hang forever if a frame. is ever lost due to, for example, （75） hardware.
（71）
A. receiver
B. controller
C. sender
D. customer
（72）
A. data
B. control
C. request
D. session
（73）
A. application
B. connection
C. stream
D. acknowledgement
（74）
A. vanish
B. vary
C. appear
D. incline
（75）
A. acting
B. working
C. malfunctioning
D. functioning
Telecommunications devices convert different types of information, such as sound and video, into electronic or optical signals. Electronic signals typically travel along a medium such as copper wire or are carried over the air as radio waves. Optical signals typically travel along a medium such as strands of glass fibers. When a signal reaches its destination, the device on the receiving end converts the signal back into an understandable message, such as sound over a telephone, moving images on a television, or words and pictures on a computer screen.
Telecommunications messages can be sent in a variety of ways and by a wide range of devices. The messages can be seat from one sender to a single receiver (point-to-point) or from one sender to many receivers (point-to-multipoint). Personal communications, such as a telephone conversation between two people or a facsimile (fax) message (see Facsimile Transmission), usually involve point-to-point transmission. Point-to-multipoint telecommunications, often called broadcasts, provide the basis for commercial radio and television programming.
Telecommunications begin with messages that are converted into electronic or optical signals. Some signals, such as those that carry voice or music, are created in an analog or wave format, but may be converted into a digital or mathematical format for faster and more efficient transmission. The signals are then sent over a medium to a receiver, where they are decoded back into a form. that the person receiving the message can understand. There are a variety of ways to create and decode signals, and many different ways to transmit signals.
Individual people, businesses, and governments use many different types of telecommunications systems. Some systems, such as the telephone system, use a network of cables, wires, and switching stations for point-to-point communication. Other systems, such as radio and television, broadcast radio signals over the air that can be received by anyone who has a device to receive them. Some systems make use of several types of media to complete a transmission. For example, a telephone call may travel by means of copper wire, fiber-optic cable, and radio waves as the call is sent from sender to receiver. All telecommunications systems are constantly evolving as telecommunications technology improves. Many recent improvements, for example, offer high-speed broadband connections that are needed to send multimedia information over the Internet.
Personal computers have pushed the limits of the telephone system as more and more complex computer messages are being sent over telephone lines, and at rapidly increasing speeds. This need for speed has encouraged the development of digital transmission technology. The growing use of personal computers for telecommunications has increased the need for innovations in fiber-optic technology.
Telecommunications and information technologies are merging and converging. This means that many of the devices now associated with only one function may evolve into more versatile equipment. This convergence is already happening in various fields. Some telephones and pagers are able to store not only phone numbers but also names and personal information abo
A．Current development.
B．Transmission of message.
C．Computer networking.
D．Government regulation.
阅读材料，回答题。
All the useful energy at the surface of the earth comes fromthe activity of the sun. The sun heats and feeds creatures and mankind. Eachyear it provides men with two hundred million tons of grain and nearly tenmillion tons of wood, coal, oil, natural gas, and all other fuels are stored energyfrom the sun. Some was collected by this season’s plants as carbon compounds.Some was stored by plants and trees ages ago. Even waterpower derives from thesun. Water turned into vapor by the sun fails as rain. It courses down themountains and is converted to electric power. Light transmits only the energythat comes from the sun’s outer layer, and much of this energy that is directedtowards the earth never arrives. About nine tenths of it is absorbed by theatmosphere of the earth. In fact, the earth itself gets only one half millionthof the sun&39;s entire output of radiant energy.
The sun is the source of all of the following EXCEPT ________ 查看材料
A.gasoline
B.natural gas
C.atomic power
D.animal fat
A) attends
B) highlights
C) buy
D) invest
E) telecommunications
F) superhighway
G) assess
H) access
I) advantage
J) privacy
K) transformation
L) transmits
M) charge
N) disposal
O) potential
Mr. Li runs a small trade company in Sichuan Province. He used to be worried about the sales of his goods, but now he simply logs on to the Internet and(1)the information about his company to almost anywhere. He now has so many resources at his(2)than before. He has even started to(3)in foreign countries and make money almost anywhere.
The(4)revolution has certainly changed the way we look at the world. And, most importantly, it allows people to get equal(5)to the information. People in less developed areas of the world are taking(6)of the benefits as well. One person says, "I used to have a small farm, but now I am doing international business." This is just one of the many benefits of the information(7). There are, however, some(8)challenges we will have to face. For example, there is a great deal of concern over(9)in the Information Age. Mr. Li(10)this point. Hopefully, we can solve this problem in the near future.
The idea that education transmits knowledge is dated back to
[A] the Renaissance humanists.
[B ] the medieval universities.
[C] the 18th century's American scholars.
[D] the cold war period.
A.activity
B.process
C.transaction
D.action
A.bending stresses
B.torsion stresses
C.shear stresses
D.All of the above
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