材料的工艺性能主要是指（）性、（）性、（）性和（）性。
参考答案：铸造；锻压；焊接；热处理
--- Nancy, can I take a look at the note you took for last period, please?
--- I’m sorry, I __________ something else then. I’ll make it up right away.
A．did
B．was doing
C．had done
D．have done
武汉轻轨车辆的空气管路系统主要由哪几部分组成？
