乳化液泵站柱塞密封处漏液严重的原因可能是()。
A.先导阀密封不良
B.密封圈损坏
C.柱塞室中心不准,表面有划伤、撞毛
D.连杆螺钉松动
参考答案:B, C
Nothing is so easy as _____ parents to raise their expectations of their children too high. [ ]
A. of
B. to
C. by
D. for
通常情况下,供电线路的允许电压损失为5%。( )