Which object may be used during query optimization to improve the performance for a subset of SELECT queries?（）
A、MQT
B、Trigger
C、Read Only Cursor
D、Stored Procedure
如果文件系统中有两个文件重名，不应采用（）。
A、单级目录结构
B、树型目录结构
C、二级目录结构
D、A和C
When defining a function activity, what is true about the Result Type?（） (Choose two.)
AResult Type is optional.
BResult Type is mandatory.
CResult Type can be changed after it is assigned to the function activity.
DResult Type should belong to the same item type as the function activity
患者，男性，52岁。行硬膜外腔阻滞腹腔镜胆囊切除术，术后患者出现剧烈背痛，进行性脊髓压迫症状，伴肌无力、尿潴留、括约肌功能障碍，继而出现完全性截瘫。首先考虑患者发生了（）
A、硬膜外血肿
B、麻醉药中毒反应
C、全脊髓麻醉
D、假性脑膜炎
E、麻醉平面过高
若两台主机在同一子网中，则两台主机的IP地址分别与它们的子网掩码相“与”的结果一定（）。
A、为全0
B、为全1
C、相同
D、不同
Which three statements correctly describe the features of the I/O calibration process?（）
AOnly one I/O calibration process can run at a time.
BIt automates the resource allocation for the Automated Maintenance Tasks.
CIt improves the performance of the performance-critical sessions while running.
DIt can be used to estimate the maximum number of I/Os and maximum latency time for the system.
EThe latency time is computed only when the TIMED_STATISTICS initialization parameter is set to TRUE.