通信管道、通道与铁路钢轨(或坡脚)的最小平行净距为()m。
A、2
B、1.5
C、1
D、0.5
Identify three situations in which you would NOT be able to drop a tablespace. ()
Awhen the tablespace is online
Bwhen the tablespace has segments with data in it
Cwhen the tablespace is a default permanent tablespace for the database
Dwhen the tablespace contains a table that is currently being used by transactions
Ewhen the tablespace contains undo data that is needed to rollback an uncommitted transaction
一个工程师在同一个ATA上面,安装两个IDE硬盘,第一个硬盘跳线设置为Master,BIOS检测到它,第二个硬盘跳线设置为Slave,但是BIOS不能检测到它,那么下一步该如何解决这个问题?()
A、换第一个硬盘
B、换第二个硬盘
C、把CD-ROM设置为Slave设
D、置第二个硬盘为Master
Which two statements about sequences are true? ()
AYou use a NEXTVAL pseudo column to look at the next possible value that would be generated from a sequence, without actually retrieving the value.
BYou use a CURRVAL pseudo column to look at the current value just generated from a sequence, without affecting the further values to be generated from the sequence.
CYou use a NEXTVAL pseudo column to obtain the next possible value from a sequence by actually retrieving the value from the sequence.
DYou use a CURRVAL pseudo column to generate a value from a sequence that would be used for a specified database column.
EIf a sequence starting from a value 100 and incremented by 1 is used by more then one application, then all of these applications could have a value of 105 assigned to their column whose value is being generated by the sequence.
FYou use REUSE clause when creating a sequence to restart the sequence once it generates the maximum value defined for the sequence.
直放站提取信号源的主要方式有哪几种:()
A、通过直放站的施主天线直接从附近基站提取信号。
B、用耦合器从附近基站耦合部分信号通过光纤传送到盲区内的直放站。
C、通过直放站的施主天线直接从附近直放站提取信号。
D、用耦合器从附近基站耦合部分信号通过电缆传送到盲区内的直放站。
用户报告说计算机工作越来越慢了,首先应该采取以下哪种措施?()
A、格式化并重装硬盘
B、备份并重新恢复硬盘
C、增加一个新硬盘,并格式化为相同的文件系统
D、使用硬盘属性下的碎片整理程序