动力荷载
参考答案：由管道振动等产生的荷载。
–When will you come home for dinner? I will prepare it for you.
--Don’t ______it. I’ll eat out with my friends.
A．care about
B．bother about
C．worry about
D．talk about
乙炔气瓶的瓶温不得越过（）℃。
A、40
B、45
C、50
D、55
