阀门的密封形式有几种?
参考答案:
1.平面密封(1)平平面密封(2)斜平面密封
2.锥面密封
3.球面密封
4.圆弧面密封
5.刀影面密封
6.圆柱面密封
—We’ve missed the train!
—________, there will be another in ten minutes.
A. I’m sorry B. Excuse me
I beg your pardon D. Never mind
连杆刚度不足,可能发生何种故障?