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搜题
【单选题】
电工仪表测出的交流电数值以及通常所说的交流电数值(如照明电压 220V )都是指的交流电的( )。A.
瞬时值
B.
最大值
C.
有效值
D.
最小值
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举一反三
【多选题】Which two statements are true regarding undo tablespaces（）
A.
The database can have more than one undo tablespace.
B.
The UNDO_TABLESPACE parameter is valid in both automatic andmanualundo management.
C.
Undo segments automatically grow and shrink as needed， acting as circular storage buffer for their assigned transactions.
D.
An undotablespaceis automatically created if the UNDO_TABLESPACEparameter is not set and the UNDO_MANAGEMENT parameter is set to AUTO during the database instance start up.