You have created a resource plan， DB_PLAN， using DBMS_RESOURCE_MANAGER.CREATE_SIMPLE_PLAN and you want to impose a restriction on utilization of resources by the database users. Which step must be performed before you can start using the resource plan？（）
A、 assign users to consumer groups
B、 set the resource plan for the instance
C、 configure a simple resource plan and specify plan directives
D、 configure a complex resource plan and specify plan directives
Using the LIST command in Recovery Manager (RMAN), which two pieces of information in the RMANrepository can be listed?（）
Astored scripts in the recovery catalog
Bbackups that can be deleted from disk
Cbackup sets and image copies are obsolete
Dbackups that do not have the AVAILABLE status in the RMAN repository RMAN
在笛卡儿坐标系中，当X轴的正向向左，Y轴和正向向上，那么Z轴的正向应向外。
A、对
B、错
在执行语句SELECT department_id FROM employees，departments WHERE employees.department_id= departments.department_id；时报错，原因是（）。
A、没有给表employees和表departments加别名
B、没有给列department_id加别名
C、不能用employees.department_id=departments.department_id作为条件
D、SELECT后面的department_id没有指定是哪个表
（）是正确的E-mail地址。
A、mailto:Webmaster@ceiaeC.org
B、Wmailto:master@ceiaec.org
C、http：//www.ceiaeC.org
D、D.http：//www.ceiaeorg
简述色彩计划的特性。