信必可主要成份之一福莫特罗是哪一类的支气管扩张剂（）
A. 长效β2受体激动剂
B. 抗组胺类药物
C. 长效/速效β2受体激动剂
D. 抗胆碱能药物
由于个人缴费基数差异较大，影响养老金水平，如何处理？
When CONFIGURE CONTROLFILE AUTOBACKUP is set to ON， RMAN automatically performs a control file autobackup in which three situations？（）
At the end of every RUN block.
B. After every SET CONTROLFILE AUTOBACKUP FORMAT command.
C. After every BACKUP or COPY command issued at the RMAN prompt.
D. At the end of every RUN block if the last command in the block was either BACKUP or COP
E. Whenever a BACKUP or COPY command within a RUN block is followed by a command that is neither BACKUP nor COP
F. After every BACKUP or COPY command within a RUN block that is followed by the CONFIGURE CONTROLFILE AUTOBACKUP FORMAT command.
冷气不够凉，检测在发动机2400r/min时，高压压力为12kg/cm2，低压压力为1.1kg/cm2，贮液器至蒸收器的冷气管结霜，请回答下列问题：正常制冷情况下，贮液器的观察窗应能见到（）现象。
A. 清澈透明
B. 初时极少量气泡，后没有气泡
C. 持续大量气泡
D. 初时极少量气泡，后气泡增多
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