多项选择题
A.Each segment contains one or more extents.
B.Multiple tablespaces can share a single data file.
C.A data block is the smallest unit of input/output （I/O） in data files.
D.It is possible to have tablespaces of different block sizes in a database.
E.Each data block in the database always corresponds to one operating system block.
单项选择题 You have set Tablespace Full Metrics Threshold values for the USERS tablespace as follows： Warning （%）： 90 Critical （%）： 95 Which background process is responsible for issuing alerts when the threshold is crossed（）
多项选择题 Whichtwostatementsaboutthebackgroundprocessofthedatabasewriteraretrue（）
单项选择题 View the Exhibit and identify the component marked with a question mark. （）