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。