爆炸的定义？
参考答案：
爆炸是物质发生急剧的物理、化学变化，在瞬间释放出大量能量并伴有巨大声响的过程。
曳引机承重梁埋入承重墙的深度应()。
A、≥75mm
B、超过墙厚中心20mm
C、A+B
D、无规定
A．The advanced equipment in the laboratory.
B．The so-early start-working hour.
C．The terrible working habit of his colleagues.
D．The interval between the start-working hours of two places.
