A.Update job log when a job completes
B.Spawn and remove job slaves
C.Write/read job info to/from memory cache
D.Query job table
E.Pass job information to job slaves
答案：（A）
解析：
《Administrator's Guide》 28.4.2 Job Coordinator actions
The job coordinator:
1. Controls and spawns the job slaves
2. Queries the job table
3. Picks up jobs from the job table on a regular basis and places them in a memory cache.
This improves performance by reducing trips to the disk
4. Takes jobs from the memory cache and passes them to job slaves for execution
5. Cleans up the job slave pool when slaves are no longer needed
6. Goes to sleep when no jobs are scheduled
7. Wakes up when a new job is about to be executed or a job was created using the CREATE_JOB procedure
8. Upon database, startup after an abnormal database shutdown, recovers any jobs that were running.
You do not need to set the time that the job coordinator checks the job table;
the system chooses the time frame automatically.
One job coordinator is used per instance. This is also the case in Oracle RAC environments.