Your multitenant container database (CDB) contains a pluggable database, HR_PDB. The default permanent tablespace in HR_PDB is USERDATA. The container database (CDB) is open and you connect RMAN. You want to issue the following RMAN command: RMAN > BACKUP TABLESPACE hr_pdb:userdata; Which task should you perform before issuing the command?（） Place the root container in ARHCHIVELOG mode.。 Take the user data tablespace offline.。 Place the root container in the nomount stage.。 Ensure that HR_PDB is open.。
利用原油和水的渗透性的差异，鉴别乳化液类型的方法是（） 染色法。 冲淡法。 电导法。 湿润法。
You have been assigned to manage a set of databases. The previous DBA did not leave you notes regarding the structure of each of the databases. While analyzing an instance， you notice that the system identifier （SID） for the instance is set to ’+ASM’. What is the purpose of this instance？（） This instance is being used to manage the operating system files.。 This instance is being used to manage the files of other databases.。 This instance is being used to manage the instances of other databases.。 This instance is being used to manage the background processes of other instances.。
知青题材反思小说基本上有两个反思角度，请举例分析其各自特点。
关于给水排水工程中砌筑结构对材料的基本要求，正确的有（）。 机制烧结砖应边角整齐、表面平整、尺寸准确，强度不低于MU10。 石料应质地坚实均匀，无风化剥落层和裂纹。 混凝土砌块应符合设计要求和相关标准规定。 砌筑砂浆应采用水泥砂浆，其强度等级应符合设计要求，且不应低于M15。 水泥应符合《砌体结构工程施工质量验收规范》GB50203--2011的规定。
Examine the command：
SQL> DBMS_STATS.SET_TABLE_PREFS（’SH’， ’CUSTOMERS’， ’PUBLISH’， ’false’）； Which statement describes the effect of the above command（）
