[多选]

The EMP table has some discrepancy in data entry with a particular employee ID. You execute the query as shown in the Exhibit to retrieve all versions of the row that exist between two SCNs.View the Exhibit.
Which two statements about the results of the query shown in the Exhibit are correct? （）(Choose two.)

You dropped a schema of a user in an Oracle 10g by mistake. You decide to flash the database back to its previous state to restore the deleted schema.   Which process writes the before images of the physical database blocks to the flashback database logs？（）  LGWR。  DBWR。  MMON。  RVWR。 风景名胜 What recommendations does the SQL Access Advisor provide for optimizing SQL queries？（）    selection of SQL plan baselines。  partitioning of tables and indexes。  creation of index-organized tables。  creation of bitmap， function-based，and B-tree indexes。  optimization of materialized views for maximum query usage and fast refresh。 为有利于石灰土强度的形成，用作路面基层的石灰土应在冰冻前（）完工。 30天。 45天。 60天。 15天。 好氧微生物需要氧气作何用？充氧效率与微生物生长有什么关系？

The EMP table has some discrepancy in data entry with a particular employee ID. You execute the query as shown in the Exhibit to retrieve all versions of the row that exist between two SCNs.View the Exhibit.
Which two statements about the results of the query shown in the Exhibit are correct? （）(Choose two.)