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Which three are true about monitoring waits for sessions and services? (Choose three.)
A. V$SESSION_EVENT displays all waits for all past and existing sessions if the wait has occurred at least once for a session.
B. V$SERVICE_EVENT displays all waits for all services if the wait has occurred at least once for a service.
C. V$SESSION_WAIT_CLASS displays waits broken down by wait class only for waiting sessions.
D. V$SESSION_WAIT and V$SESSION both contain details of the event on which a non-waiting session last waited.
E. V$SESSION_EVENT displays all waits for all past sessions if the wait has occurred at least once for a session.
F. V$SESSION_WAIT and V$SESSION both contain details of the event on which a session is currently waiting.

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BCF:

V$SESSION_WAIT_CLASS displays the time spent in various wait event operations on a per-session basis.
V$SESSION_WAIT displays the current or last wait for each session.
V$SESSION displays session information for each current session.