QUESTION NO: 94
What is an obsolete backup set?
A. A backup set that is missing one or more backup set pieces
B. A backup that has exceeded the retention criteria and is no longer needed
C. A backup set that does not include archived redo logs
D. A backup set that can not be recovered due to corruption
E. A backup set superceded by a datafile copy
Answer: B
过时的备份集是什么？
B.已经超过了保留条件，不再需要的备份
原文：http://blog.csdn.net/xuejiayue1105/article/details/48904159