法兰规格:11″-15M279.4,2FZ28-105封井器的钢圈环号()。
A.BX158
B.BX159
C.BX160
D.R73(RX73)
参考答案:A
I will go home ____________ June twenty-fifth.[ ]
A. in
B. at
C. of
D. on
填料密封有什么特点?