论述往复式压缩机润滑的目的。
You conned using SQL Plus to the root container of a multitenant container database (CDB) with SYSDBA privilege. The CDB has several pluggable databases (PDBs) open in the read/write mode. There are ongoing transactions in both the CDB and PDBs. What happens alter issuing the SHUTDOWN TRANSACTIONAL statement?（） The shutdown proceeds immediately. The shutdown proceeds as soon as all transactions in the PDBs are either committed or rolledhack.。 The shutdown proceeds as soon as all transactions in the CDB are either committed or rolled back.。 The shutdown proceeds as soon as all transactions in both the CDB and PDBs are either committed or rolled back.。 The statement results in an error because there are open PDBs.。
防水卷材起鼓的原因是（） 基层的水分大。 粘结剂胶合不牢。 底层空气未排净。 搭接不到位。
开关燃弧时间与刚分速度关系是（）。 .正比。 无关。 反比。
You executed the following command in Recovery Manager （RMAN）： RMAN> RESTORE CONTROLFILE； Which operation must you perform before this command is executed？（） back up the control file to trace。 bring database to the MOUNT state。 open a connection to the RMAN recovery catalog， which contains the RMAN metadata for the target database。 set the database ID （DBID）， but only if the DB_NAME parameter associated with the target database is unique in the recovery catalog。
协调性训练程序中错误的是：（）
