A. occurs under cyclic loading B. is unaffected by sharp angles in a material C. only occurs in resin composites D. all of the above
A. 冒涨 B. 裂纹 C. 夹杂 D. 缩孔
A. 稳定电压 B. 稳定电流 C. 稳定电器 D. 稳定电弧
A. 0° B. 45° C. 90° D. 135°
A. 碳脱氧 B. 硅脱氧 C. 锰脱氧