Which of the following is a prerequisite for running DBMS_TDB.CHECK_DB to a successful completion？（）

A、 The database must be in read-write mode.

B、 The database must have no external files.

C、 The database must open in read-only mode.

D、 The database must be mounted but not opened.

A database is running In ARCHIVBXXMS mode. It has two online redo log groups and each group has one member.  A LGWR Input/output （I/O） fells due to permanent media failure that has resulted In the loss of redo log file and the LWGR terminates causing the instance to crash. The steps to recover from the loss of a current redo log group member in the random order are as follow.   1） Restore the corrupted redo log group. 2） Restore from a whole database backup.  3） Perform incomplete recovery.  4） Relocate by renaming the member of the damaged online redo log group to a new location.  5） Open the database with the RESETLOGS option.  6） Restart the database instance.  7） Issue a checkpoint and clear the log.   Identify the option with the correct sequential steps to accomplish the task efficiently（）.  

A、 1，3，4，and 5

B、 7，3，4. and 5

C、 2，3，4，and 5

D、 7，4，3，and 5

E、 Only 6 is required

金黄色葡萄球菌肺炎患儿在治疗过程中突然出现呼吸困难加重，经吸痰和给予氧气吸入后无明显缓解，应考虑可能是（）

A、肺部炎症加重

B、并发脓气胸

C、高热所致

D、并发心力衰竭

E、呼吸性酸中毒

Once the TCP connection is established, which message type initiates the BGP peering process?（）

A、Open

B、Active

C、Update

D、Keepalive

E、Notification

What is the purpose of the OSPF link-state update packet?（）

A、describes a change to the OSPF hello timer

B、carries one or more link-state advertisements

C、establishes and maintains neighbor relationships

D、describes the contents of the entire link-state database

In the OSI model, which of the following layers would be the cause of a session time-out while browsing the web?（）

A、Laye r2

B、Layer 3

C、Layer 5

D、Layer 7