下面哪个功能键可以调出Delphi 的联机帮助信息（） F1键。 F2键。 F3键。 F4键。
目前采油累积量与地质储量的百分比称为（） 采收率。 采出程度。 目前采收率。
You are using the following command to clear the log file group： ALTER DATABASE CLEAR LOFFILE GROUP 2； In which case would the command be successful？（） Group 2 is the active group.。 Group 2 is the current group.。 Database is in the MOUNT state.。 Group 2 has been already archived.。
You are connected to a pluggable database (PDB) as a common user with DBA privileges. The STATISTICS_LEVEL parameter is PDB_MODIFIABLE. You execute the following: SQL > ALTER SYSTEM SET STATISTICS_LEVEL = ALL SID = ‘*’ SCOPE = SPFILE; Which is true about the result of this command?（） The STATISTICS_LEVEL parameter is set to all whenever this PDB is re-opened.。 The STATISTICS_LEVEL parameter is set to ALL whenever any PDB is reopened.。 The STATISTICS_LEVEL parameter is set to all whenever the multitenant container database (CDB) is restarted.。 Nothing happens; because there is no SPFILE for each PDB, the statement is ignored.。
造成发电机失步的非振荡的主要原因有哪些？
When is an implicit anchor created?（）
