单项选择题
How many database instances are used during a database-duplication process？（）
A. One B. Two C. Three D. Four E. Five
单项选择题 Which of the following commands will perform an active database duplication of the ORCL database to the ORCL2 database？（）
单项选择题 Whenyoureperformingactivedatabaseduplication，abackupofwhatkindisrequired？（）
单项选择题 Whichcommandisusedtobeginatablespacepoint-in-timerecovery？（）
