A)They are gathered by the Manageability Monitor(MMON) background process.
B)They can be gathered by executing the PL/SQL procedures in the DBMS_STATES package.
C)They do not persist across instance restarts.
D)They can be used to determine the events on which a database instance waited.
E)They provide information to the Optimizer so that it can determine optimal execution plans for SQL statements.
F)They are automatically updated when DDL statements execute.
Answer: BE
原文：https://blog.51cto.com/13854012/2424719