阀门法兰螺栓孔中心偏差不应超过孔径的(),以保证螺栓的自由穿人,防止损伤螺栓纹。
A.2%
B.3%
C.5%
D.8%
参考答案:C
. Great ____have been made in the field of computer science in the past decades.
A.progress
B.breakthroughs
C.mistakes
D.assessments
炼焦工业发展的方向和新技术有哪些?