压缩机润滑油油路系统的储压器应充氮气到规定压力并保持（）小时检查无泄漏。
A.6
B.12
C.24
D.48
参考答案：B
可以在血清中检测的小细胞肺癌较为特异的肿瘤标志物是（）。
A.CEA
B.CA125
C.SCC–Ag
D.CA19–9
E.NSE
The white man who was put in prison for trying to __________the headquarters(总部)of the ANC tried to escape but failed.
A．set up
B．break up
C．fire up
D．blow up
