A user complains that a computer monitor is experiencing a jitter. Replacing the monitor and video card does not fix the problem. Which of the following could be causing the problem？（）

单项选择题AclientasksatechniciantoaddaDVD+Rburnertoacomputersystem.Thetechniciandoesthisandsuccessfullyteststhedrive.Threeweekslater，theclientcallsandsaysthattheburnerisnolongerworking.ThetechnicianlearnsthatthedrivereadsCDsandDVDs，butwillnolongerburnDVDs.Whenarrivingonsite，whatistheFIRSTactionthatthetechnicianshouldtake？（）

A.check for a faulty IDE cable
B.be sure that the DVD+R is formatted before using it
C.check for incompatible media
D.re-install the DVD burning software

单项选择题Whichcomponentsaredesignedtobeconvenientlyreplacedbyaservicetechnician？（）

A.SMDs（surface mounted devices）
B.FRUs（field replacement units）
C.FESs
D.BEMs

单项选择题Whichtestchecksthetransmitterandreceiverofalocalmodem？（）

A.data parity
B.analog loop back
C.local digital loop back
D.remote digital loop back

单项选择题Acomputerbootsupwiththeerror CMOSChecksumFailure. Whichofthefollowingcomponentsneedstobereplaced？（）

A.power supply
B.CMOS chip
C.motherboard
D.CMOS battery

单项选择题AnA+CertifiedTechnicianMUSTdoaninstallonaWindowsXPsystemfromthedistributionCD.However，thesystemdoesnotbootfromthisCD.WhatistheMOSTlikelycauseofthisproblem？（）

A.The CD is defective.
B.The CD is not bootable.
C.The CD-ROM drive is defective.
D.The Boot Sequence is not set in the BIOS to boot first from the CD