You have backed up your database using image copies. You have lost the SYSTEM tablespace and need to restart your database as quickly as possible. What is the correct solution?
A. Restore the SYSTEM tablespace from the last backup set and then recover the database.
B. Restore the SYSTEM tablespace image copy using the restore command and then restore the
database.
C. Use the switch datafile command to instantly switch to the datafile copy, recover the tablespace, and open the database.
D. The database is not recoverable in this situation with image copies.
E. Manually copy the datafile image copy to the correct location and then manually restore the database from SQL*Plus.
因为是 image copy，可以使用 switch 命令，切换 system 数据文件的地址，然后 recover，
再打开数据库。使用 switch 命令可以快速切换数据文件的地址。
注:RAMN备份类型 https://www.2cto.com/database/201304/205043.html
原文：http://www.cnblogs.com/Babylon/p/7815166.html