体育教学活动应控制好活动时间，一般小班为（）分钟。
A. 15～20
B. 20～25
C. 25～30
D. 40～45
当抽油井井口装有无线回压传感器时，RTU中L8状态指示灯闪烁或50s亮灭一次表示（）传感器井口回压有数据接收。
A. 无线载荷
B. 无线死点开关
C. 无线温度
D. 无线压力
In which scenario will you use the Flashback Version Query feature？（）
A. when you want to restore a table that has been dropped from the Recycle Bin
B. when you want to identify the transaction ID of the transaction that deleted some important records from a table
C. when you want to recover the schema of a dropped user
D. when you want to restore a dropped tablespace
教育对文化的正向功能有（）。
A. 保存
B. 融合
C. 选择
D. 创造
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