喷煤车间生产厂房，火灾危害的防火，防暴建筑设计属于（）类防火、防暴规范。
参考答案：乙
I walked into class, the teacher had started teaching already. [ ]
A. By the time
B. While
C. After
D. Because
在自由锻的基本工序中，常用的是：______、______和冲孔。
