多项选择题 Whicharetheprerequisitesforperformingflashbacktransactionsonyourdatabase？（）

多项选择题 You are managing an Oracle Database 11g database with ASM storage. The ASM disk group has the COMPATIBLE.ASM attribute set to 11.1.  Which statements are true regarding extent management and allocation units in the ASM disk group？（）

单项选择题 You want to track and store all transactional changes to a table over its lifetime. To accomplish this task， you enabled Flashback Data Archive with the retention of 5 years. After some time， the business requirement changed and you were asked to change the retention from 5 years to 3 years. To accomplish this， you issued the following command：   ALTER FLASHBACK ARCHIVE fla1 MODIFY RETENTION 3 YEAR；   What is the implication of this command？（）