● The Hertz is used as a unit to measure （93） .
（93）A.frequency    B.packet loss      C.cell         D.phase
 
● Inside the  Internet, the data is routed to the computer via network devices called （94） .
（94）A.servers      B.operators    C.filters      D.routers
 
● Early cellular systems were （95） .They operated by directly modulating a voicewaveform on a carrier and transmitting it.Different cell phones in the same cell were assigned different carrier frequencies, and adjacent cells used different set of （96） .
（95）A.digital       B.numerical     C.analog        D.quantized
（96）A.time slots    B.antennas      C.frequencies   D.codes
 
● A satellite system is composed basically （97） a satellite in space and many earth stations on the ground which links to it.
（97）A.with          B.by            C.of            D.as
 
● 阅读下面的短文，回答98~100题
　　【Until the  popular adoption  of  mobile  phones in 1990s, pagers  fulfilled the role  of common  personal and  mobile communications. Today,  pagers  mainly support the “critical messaging”  markets.They are the ideal solution  for very quick, very reliable personal  or group  messaging. Unlike  many  other  mobile  communications  networks,  they  continue  to work in times of emergency or disaster as they do not suffer from network overload as has been proven many times.For this reason, they are still very popular with emergency service personal, medical personal, and information technology support staff.】 Since 1990, pagers have started to become （98） than before.Pagers are the ideal solution for （99） .It has been proven many times that （100） .
（98）A.more popular       B.less popular
           C.more reliable       D.less reliable

（99）A.emergency service  B.Web browsing    
           C.medical image         D.information processing

（100）A.pagers can reduce network overload
             B.pagers do not suffer from network overload
             C.disaster can reduce network overload
             D.disaster do not suffer from network overload