282、Operation system

332、broadband

331、The coaxial cable is the common transmission medium.It has better shielding than twisted pairs, so it can span longer distances at higher speeds.Two kinds of coaxial cable are widely used.One kind, 5 0— ohm cable, is commonly used for digital transmission.The other kind, 7 5— ohm cable, is commonly used for analog transmission.This distinction is based on historical, rather than technical , factors ( e.g.early dipole antennas had an impedance of 3 0 0ohm, and it was easy to build 4:1 impedance matching transformers).A coaxial cable consists of a stiff copper wire as the c o r e , s u r r o u n d e d by an insulating material.The insulator is encased by a cylindrical conductor, often as a closely woven metal mesh.The outer conductor is covered in a protective plastic sheath.The construction and shielding of the coaxial cable give it a good combination of high bandwidth and excellent noise immunity.The bandwidth possible depends on the cable length.For 1 — km cables a data rate of 1 to 2 Gbps is feasible.Longer cables can also be used, but only at lower data rates or with periodic amplifiers.Coaxial cables used to be widely used within the telephone system but have now largely been replaced by fiber optics on long— haul routes.In the United States alone, 1000 km of fiber is installed every day ( counting a 100— km bundle with 10 strands of fiber as 1000 km).Sprint is alread y 100 percent fiber, and the other major carriers are rapidly approaching that.Coax is still widely used for cable television and some local area networks, however(5)、Which of the following is true?

331、The coaxial cable is the common transmission medium.It has better shielding than twisted pairs, so it can span longer distances at higher speeds.Two kinds of coaxial cable are widely used.One kind, 5 0— ohm cable, is commonly used for digital transmission.The other kind, 7 5— ohm cable, is commonly used for analog transmission.This distinction is based on historical, rather than technical , factors ( e.g.early dipole antennas had an impedance of 3 0 0ohm, and it was easy to build 4:1 impedance matching transformers).A coaxial cable consists of a stiff copper wire as the c o r e , s u r r o u n d e d by an insulating material.The insulator is encased by a cylindrical conductor, often as a closely woven metal mesh.The outer conductor is covered in a protective plastic sheath.The construction and shielding of the coaxial cable give it a good combination of high bandwidth and excellent noise immunity.The bandwidth possible depends on the cable length.For 1 — km cables a data rate of 1 to 2 Gbps is feasible.Longer cables can also be used, but only at lower data rates or with periodic amplifiers.Coaxial cables used to be widely used within the telephone system but have now largely been replaced by fiber optics on long— haul routes.In the United States alone, 1000 km of fiber is installed every day ( counting a 100— km bundle with 10 strands of fiber as 1000 km).Sprint is alread y 100 percent fiber, and the other major carriers are rapidly approaching that.Coax is still widely used for cable television and some local area networks, however(4)、What is the main topic of this passage?

331、The coaxial cable is the common transmission medium.It has better shielding than twisted pairs, so it can span longer distances at higher speeds.Two kinds of coaxial cable are widely used.One kind, 5 0— ohm cable, is commonly used for digital transmission.The other kind, 7 5— ohm cable, is commonly used for analog transmission.This distinction is based on historical, rather than technical , factors ( e.g.early dipole antennas had an impedance of 3 0 0ohm, and it was easy to build 4:1 impedance matching transformers).A coaxial cable consists of a stiff copper wire as the c o r e , s u r r o u n d e d by an insulating material.The insulator is encased by a cylindrical conductor, often as a closely woven metal mesh.The outer conductor is covered in a protective plastic sheath.The construction and shielding of the coaxial cable give it a good combination of high bandwidth and excellent noise immunity.The bandwidth possible depends on the cable length.For 1 — km cables a data rate of 1 to 2 Gbps is feasible.Longer cables can also be used, but only at lower data rates or with periodic amplifiers.Coaxial cables used to be widely used within the telephone system but have now largely been replaced by fiber optics on long— haul routes.In the United States alone, 1000 km of fiber is installed every day ( counting a 100— km bundle with 10 strands of fiber as 1000 km).Sprint is alread y 100 percent fiber, and the other major carriers are rapidly approaching that.Coax is still widely used for cable television and some local area networks, however(3)、Now_______have replaced coaxial cables on long - haul routes.

331、The coaxial cable is the common transmission medium.It has better shielding than twisted pairs, so it can span longer distances at higher speeds.Two kinds of coaxial cable are widely used.One kind, 5 0— ohm cable, is commonly used for digital transmission.The other kind, 7 5— ohm cable, is commonly used for analog transmission.This distinction is based on historical, rather than technical , factors ( e.g.early dipole antennas had an impedance of 3 0 0ohm, and it was easy to build 4:1 impedance matching transformers).A coaxial cable consists of a stiff copper wire as the c o r e , s u r r o u n d e d by an insulating material.The insulator is encased by a cylindrical conductor, often as a closely woven metal mesh.The outer conductor is covered in a protective plastic sheath.The construction and shielding of the coaxial cable give it a good combination of high bandwidth and excellent noise immunity.The bandwidth possible depends on the cable length.For 1 — km cables a data rate of 1 to 2 Gbps is feasible.Longer cables can also be used, but only at lower data rates or with periodic amplifiers.Coaxial cables used to be widely used within the telephone system but have now largely been replaced by fiber optics on long— haul routes.In the United States alone, 1000 km of fiber is installed every day ( counting a 100— km bundle with 10 strands of fiber as 1000 km).Sprint is alread y 100 percent fiber, and the other major carriers are rapidly approaching that.Coax is still widely used for cable television and some local area networks, however(2)、Coaxial cable h a s _______shielding than twisted pairs, so it can span longer distances at higher speeds.

331、The coaxial cable is the common transmission medium.It has better shielding than twisted pairs, so it can span longer distances at higher speeds.Two kinds of coaxial cable are widely used.One kind, 5 0— ohm cable, is commonly used for digital transmission.The other kind, 7 5— ohm cable, is commonly used for analog transmission.This distinction is based on historical, rather than technical , factors ( e.g.early dipole antennas had an impedance of 3 0 0ohm, and it was easy to build 4:1 impedance matching transformers).A coaxial cable consists of a stiff copper wire as the c o r e , s u r r o u n d e d by an insulating material.The insulator is encased by a cylindrical conductor, often as a closely woven metal mesh.The outer conductor is covered in a protective plastic sheath.The construction and shielding of the coaxial cable give it a good combination of high bandwidth and excellent noise immunity.The bandwidth possible depends on the cable length.For 1 — km cables a data rate of 1 to 2 Gbps is feasible.Longer cables can also be used, but only at lower data rates or with periodic amplifiers.Coaxial cables used to be widely used within the telephone system but have now largely been replaced by fiber optics on long— haul routes.In the United States alone, 1000 km of fiber is installed every day ( counting a 100— km bundle with 10 strands of fiber as 1000 km).Sprint is alread y 100 percent fiber, and the other major carriers are rapidly approaching that.Coax is still widely used for cable television and some local area networks, however(1)、Two kinds of coaxial cable are widely used.One kind 50— ohm cable is commonly used fortransmission.The other k i n d , 7 5 — o h m cable is commonly used fortransmission

330、Computer office systems are computers and their peripheral equipment are used to crea te, store, process, or communicate information in a business environment.This information can be electronically produced, duplicated, and transm itted.The rapid growth of the service sector of the United States economy beginning in the mid 1 9 7 0s has furnished a new market for sophisticated office automation.With the increasing incorporation of microchips and microcircuitry into office equipm ent, the line between the computer and other equipment has blurred.At the same tim e, computers either stand alone or as part of a network and specialized software programs are taking over tasks such as facsimile transmission— or FA X, voice m ail, and telecommunications that were once performed by separate pieces of equipm ent.In fa c t, the computer has virtually taken the place of typewriters, calculators, and manual accounting techniques and is rapidly taking over graphics design, production scheduling, and engineering design as well.During the first half of the 2 0 th century, financial and other numerical re-cord keeping tasks were performed manually or by bookkeeping m achines, billingmachines, tabulation equipment, and other types of electromechanical accounting devices.In the 1950s , such machines were increasingly replaced by mainframe computers— large, very expensivehigh speed machines that required operators as well as a special temperature regulated facility to prevent overheating.Use of these machines today is limited to large organizations with heavy volume data processing requirements.Time sharing, allowing more than one company to use the same mainframe for a fee, was instituted to divide the cost of the equipment among several users while ensuring that the equipment is utilized to the maximum extent.Mainframes with remote terminals, each with its own monitor, became available in the mid 1970s and allowed for simultaneous input by many users.With the advent of the minicomputer, however, a far less expensive alternative became available.The transistor and microelectronics made manufacture of these smaller, less complex machines practicable.Minicomputer, the first of which entered general business use in the early 1960s , are now widespread in commerce and government.Terminals linked to the central processing unit ( ) are under the direct control of the individual user rather than centralized staff.In recent years, however, it is the microcomputer, or personal computer ( ), that has come to play the principal role in most office workplaces.(5)、What has come to play an important role in most offices recently?

330、Computer office systems are computers and their peripheral equipment are used to crea te, store, process, or communicate information in a business environment.This information can be electronically produced, duplicated, and transm itted.The rapid growth of the service sector of the United States economy beginning in the mid 1 9 7 0s has furnished a new market for sophisticated office automation.With the increasing incorporation of microchips and microcircuitry into office equipm ent, the line between the computer and other equipment has blurred.At the same tim e, computers either stand alone or as part of a network and specialized software programs are taking over tasks such as facsimile transmission— or FA X, voice m ail, and telecommunications that were once performed by separate pieces of equipm ent.In fa c t, the computer has virtually taken the place of typewriters, calculators, and manual accounting techniques and is rapidly taking over graphics design, production scheduling, and engineering design as well.During the first half of the 2 0 th century, financial and other numerical re-cord keeping tasks were performed manually or by bookkeeping m achines, billingmachines, tabulation equipment, and other types of electromechanical accounting devices.In the 1950s , such machines were increasingly replaced by mainframe computers— large, very expensivehigh speed machines that required operators as well as a special temperature regulated facility to prevent overheating.Use of these machines today is limited to large organizations with heavy volume data processing requirements.Time sharing, allowing more than one company to use the same mainframe for a fee, was instituted to divide the cost of the equipment among several users while ensuring that the equipment is utilized to the maximum extent.Mainframes with remote terminals, each with its own monitor, became available in the mid 1970s and allowed for simultaneous input by many users.With the advent of the minicomputer, however, a far less expensive alternative became available.The transistor and microelectronics made manufacture of these smaller, less complex machines practicable.Minicomputer, the first of which entered general business use in the early 1960s , are now widespread in commerce and government.Terminals linked to the central processing unit ( ) are under the direct control of the individual user rather than centralized staff.In recent years, however, it is the microcomputer, or personal computer ( ), that has come to play the principal role in most office workplaces.(4)、The purposes for several users to share a mainframe a re_______•

330、Computer office systems are computers and their peripheral equipment are used to crea te, store, process, or communicate information in a business environment.This information can be electronically produced, duplicated, and transm itted.The rapid growth of the service sector of the United States economy beginning in the mid 1 9 7 0s has furnished a new market for sophisticated office automation.With the increasing incorporation of microchips and microcircuitry into office equipm ent, the line between the computer and other equipment has blurred.At the same tim e, computers either stand alone or as part of a network and specialized software programs are taking over tasks such as facsimile transmission— or FA X, voice m ail, and telecommunications that were once performed by separate pieces of equipm ent.In fa c t, the computer has virtually taken the place of typewriters, calculators, and manual accounting techniques and is rapidly taking over graphics design, production scheduling, and engineering design as well.During the first half of the 2 0 th century, financial and other numerical re-cord keeping tasks were performed manually or by bookkeeping m achines, billingmachines, tabulation equipment, and other types of electromechanical accounting devices.In the 1950s , such machines were increasingly replaced by mainframe computers— large, very expensivehigh speed machines that required operators as well as a special temperature regulated facility to prevent overheating.Use of these machines today is limited to large organizations with heavy volume data processing requirements.Time sharing, allowing more than one company to use the same mainframe for a fee, was instituted to divide the cost of the equipment among several users while ensuring that the equipment is utilized to the maximum extent.Mainframes with remote terminals, each with its own monitor, became available in the mid 1970s and allowed for simultaneous input by many users.With the advent of the minicomputer, however, a far less expensive alternative became available.The transistor and microelectronics made manufacture of these smaller, less complex machines practicable.Minicomputer, the first of which entered general business use in the early 1960s , are now widespread in commerce and government.Terminals linked to the central processing unit ( ) are under the direct control of the individual user rather than centralized staff.In recent years, however, it is the microcomputer, or personal computer ( ), that has come to play the principal role in most office workplaces.(3)、What promoted the development of computer office systems?

330、Computer office systems are computers and their peripheral equipment are used to crea te, store, process, or communicate information in a business environment.This information can be electronically produced, duplicated, and transm itted.The rapid growth of the service sector of the United States economy beginning in the mid 1 9 7 0s has furnished a new market for sophisticated office automation.With the increasing incorporation of microchips and microcircuitry into office equipm ent, the line between the computer and other equipment has blurred.At the same tim e, computers either stand alone or as part of a network and specialized software programs are taking over tasks such as facsimile transmission— or FA X, voice m ail, and telecommunications that were once performed by separate pieces of equipm ent.In fa c t, the computer has virtually taken the place of typewriters, calculators, and manual accounting techniques and is rapidly taking over graphics design, production scheduling, and engineering design as well.During the first half of the 2 0 th century, financial and other numerical re-cord keeping tasks were performed manually or by bookkeeping m achines, billingmachines, tabulation equipment, and other types of electromechanical accounting devices.In the 1950s , such machines were increasingly replaced by mainframe computers— large, very expensivehigh speed machines that required operators as well as a special temperature regulated facility to prevent overheating.Use of these machines today is limited to large organizations with heavy volume data processing requirements.Time sharing, allowing more than one company to use the same mainframe for a fee, was instituted to divide the cost of the equipment among several users while ensuring that the equipment is utilized to the maximum extent.Mainframes with remote terminals, each with its own monitor, became available in the mid 1970s and allowed for simultaneous input by many users.With the advent of the minicomputer, however, a far less expensive alternative became available.The transistor and microelectronics made manufacture of these smaller, less complex machines practicable.Minicomputer, the first of which entered general business use in the early 1960s , are now widespread in commerce and government.Terminals linked to the central processing unit ( ) are under the direct control of the individual user rather than centralized staff.In recent years, however, it is the microcomputer, or personal computer ( ), that has come to play the principal role in most office workplaces.(2)、.Computer office systems can deal w ith_______in a business environment