()属于偶然性因素的范畴。
A.原材料性质的微小差异
B.机具设备的正常磨损
C.模具的微小变形
D.操作方法的微小变化
E.机具规格和品种有误
参考答案:A, B, C, D
— Li Peng, we'll take an examination in physics next week.
— Yes, but don't be nervous. ____________. [ ]
A. It doesn't matter
B. All the best
C. Take it easy
D. Take your chances
地下民用建筑的疏散走道,其顶棚、墙面和地面的装修材料采用燃烧性能为()级装修材料。
A.A
B.B1
C.B2
D.B3