二级耐火等级厂房中的房间隔墙,当采用难燃烧体时,其耐火极限应提高()。
A.0.25h
B.0.5h
C.0.75h
D.1.0h
参考答案：A
So sudden ________ that the enemy had no time to escape.[ ]
A. did the attack
B. the attack did
C. was the attack
D. the attack was
简述点数法的缺点。
