凝结水过冷却,使凝结水易吸收(),结果使凝结水的()增加,加快设备管道系统的(),降低了设备使用的安全性和可靠性。
参考答案:空气、含氧量、锈蚀
According to the school rules, no student _____ go out of the school after nine o'clock at night
without the teacher's permission.
[ ]
A. shall
B. will
C. must
D. may
发动机正常工作时,怠速机油压力不应小于()MPa
A.0.10
B.0.30
C.0.50
D.0.70