Which three tasks can be performed using a duplicate database? （）(Choose three.)
ATesting the backup and recovery procedures
BTesting the upgrade of an Oracle database to a new release
CTesting the effect of an application changes on database performance
DContinuously updating archive log files from the target database to support failover
Which of the following connectors would be used if the EIA/TIA 568 scheme is followed?（）
A、ST
B、RJ-11
C、RJ-45
D、MT-RJ
会造成"灰婴综合征"的药物是（）
A、氨茶碱
B、氯霉素
C、维生素K
D、链霉素
E、肾上腺皮质激素
患儿女，7岁。低热、轻咳3周。查体：体温38.5℃，营养差，左背下部听诊呼吸音减低，接种过卡介苗，PPD试验（+++）。其弟弟3岁，无症状，但PPD试验（+++），胸片正常，宜采取的措施是（）
A、口服异烟肼6个月
B、注射丁胺卡那2周
C、口服利福平6个月
D、口服利福平+异烟肼6个月
E、口服利福平+异烟肼4个月
网络地址172.16.0.0，要求提供100个子网地址和500台主机地址，以下哪个掩码能够实现并且没有多余地址浪费（）。
A、255.255.255.0
B、255.255.254.0
C、255.255.252.0
D、255.255.0.0
A user connecting a laptop to a wall jack is prompted for user credentials before being grantedaccess to the network. Which of the following is MOST likely implemented on the switch?（）
A、MAC filtering
B、PoE
C、IP filtering
D、802.1X