SC升降机，当需要调整提升齿轮副的啮合间隙时，是靠调整()达到的
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概率安全评价(PSA)所考虑的核动力厂始发事件的确定可以采取()种方法。
A. 2
B. 3
C. 4
D. 5
井下电机车运输爆破材料时，机车的行驶速度不得超过()米/秒。
A. 3
B. 4
C. 2
The rated operating time of a self-contained breathing device may be reduced in actual use
A. pressure differences in the atmosphere
B. the length of the hose attached to the facepiece
C. the physical exertion of the person wearing the device
D. spaces containing poisonous vapors
HPB235级钢筋采用双面帮条焊的最小帮条长度为()。A4d
B5d
C8d
DlOd
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