Which daemon converts Remote Procedure Call （RPC） program numbers into Internet port numbers？（） ["inetd","rexecd","routed","portma"]
What does the DB_FLASHBACK_RETENTION_TARGET parameter configure？（） [" An upper limit on how far you can flash back the database，depending on the information in the redo logs"," An upper limit on how far you can flash back the database，depending on the information in the undo tablespace"," The amount of time for which the flashback data is to be kept in the flash recovery area， provided that there is enough space"," The amount of time for which the flashback data is guaranteed to be kept in the undo tablespace，provided that there is enough space"]
When line errors occur, which of the following commands should be sued to cause init to re-read the /etc/inittab file if init stops respawning the getty process on a TTY?（） ["alog","telinit","sysinit","cfgmgr"]
维生素无论添加量多少都不会造成毒性作用。
城市文化冲突具有（）的特点。 ["普遍性","时代性","世界性","民族性","区域性"]
请简述无功补偿的原理及主要的补偿方式.
